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A MANUAL 


OF 


PRACTICAL ASSAYING. 


BY 


Pee VA NSE ICU LAN: (EM. 


Late Professor of Mining and Metallurgy, Colorado State School of Mines; Late Chemist 
and Assayer of the Germania Lead Works, Salt Lake City, Utah, Late Chemist and 
assistant Metallurgist of the Rio Grande Smelting Works, Socorro, M. N.; 

Late Chentist of the Globe Smelting and Kefining Co., Denver, Colo.; 

Late Chief Assayer of the United States Mint, Denver, Colo.; 

Late Superintendent and Metallurgist of the Compania 
Minera de Penoles, Mapimi, Mexico; Member 
of the American Ilxstitute of Mining 
Lngineers ; Member of the Colo- 
rado Sctentific Society ; ete. 


FIFTH EDITION, REVISED AND ENLARGED. 


FIFTH THOUSAND. 


NEW YORK: 
JOHN WILEY & SONS: 
Lonpon: CHAPMAN & HALL, LIMITED. 
1905 








Copyright, 1893, 
BY 
ts He Van F, Furman. 








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ROBERT DRUMMOND, ELECTROTYPER AND PRINTE 


R, NEY 
oe) 





Pern TO THE FIFTH EDITION. 


WHILE there have been no very marked changes in this 
edition, yet the work has been carefully examined, some 
typographical errors have been corrected, and some modifica- 
tions have been made in certain parts, due to the description 
of new methods. There have also been added Appendices 
F and G. 

At the present time the concentration of gold ores is a 
subject of great importance in the United States and else- 
where, and as the assayer may frequently be called upon to 
make laboratory tests Appendix F has been incorporated. 
It contains the mechanical assay of gold and silver ores by 
a combination of the processes of amalgamation and concen- 
tration; these are described at some length and are illus- 
trated by diagrams, with certain necessary tables, and the 
latest available data have been added. 

Appendix G contains the calculation of copper-matte 
blast-furnace charges; also valuable material, derived from 
actual experience. This matter was originally published by 
the author in the School of Mines Quarterly of Columbia 
University. The article is now out of print and has been 
incorporated in ‘‘ Practical Assaying’’ because the author 
has received numerous requests from chemists and metallur- 
gists for reprints. 

It is believed that the work is now quite abreast of the 
latest investigations and discoveries in the subject treated. 


H. VAN F. FURMAN. 
309 BOSTON BUILDING, DENVER, COLO., 


November, 1899. 
ili 


PREFACE TO THE FOURTH EDI TiGas 


IN presenting the present edition of ‘Practical Assaying ” 
to the public it is but proper to state that the work has been 
revised and a number of the chapters have been entirely re- 
written. The most important changes have been made in the 
chapters on the determination of lead, copper, bismuth, iron, 
zinc, and gold and silver in ores and copper products, the assay 
of gold bullion and the assay of platinum alloys. 

The matter contained in the Appendix is new to the pres- 
ent edition. 

In conclusion, I wish to acknowledge my indebtedness te 
numerous friends for their kind suggestions and criticisms and 
particularly to Mr. William Orr, of the Gold and Silver Ex- 
traction Co. of America, and Mr. Philip Argall, of the Metal- 
lic Extraction Co., of Florence, Colo., for much of the mattes 
contained in Appendix D. 

H. VAN F. FURMAN. 

DENVER, COLO., March, 1896, f 


iv 


PREFACE. 


SOME three years ago there was published in The Mining 
Industry of Denver, by the author of the present volume, a 
series of articles entitled “Notes on Technical Chemical 
Analyses.’’ The articles were favorably received by the tech- 
nical public, and in compliance with numerous requests their 
republication in the present book form was undertaken. 

It is, however, proper to state that the original articles 
have been rewritten and much new matter has been added, 
embracing all the new technical methods which have been in- 
troduced and proved trustworthy since the publication of the 
series referred to, as well as many determinations not described 
there. 

Greatest prominence has been given to the rapid methods 
in vogue in the technical laboratories of the United States, 
supplemented by a detailed description of some of the longer 
and more exact ones. 

Although the plan of the work presupposes a knowledge of 

the general principles of chemistry, the endeavor has been to 
present the methods in a form that those having but a more 
limited experience in analytical chemistry could successfully 
perform the operations. 
- Chapter III of Part IV, while not strictly within the scope 
of a work of the present nature, was included to illustrate the 
practical application of the principles of stoichiometry and 
chemistry to metallurgy. 

Reference nas been made by footnotes to the original sources 


Vv 


v1 PREFACE. 


of information. Where, inadvertently, omissions have occurred 
and due credit has not been so given, the author would esteem 
it a favor to have his attention called to the neglect. He 
would also be pleased to receive criticisms on the work, so that 
he may be able to take advantage of them should a future 
edition be called for. 

In conclusion the author begs to add that should this little 
volume fill even partially the wants of technical chemists and 
meet with their approval, he will feel amply repaid for the 
labor involved in the compilation and publication of the 
methods described. 


H. VAN F. FURMAN. 
DENVER, COLO., September 30, 1893. 


TABLE OF CONTENTS. 


PART I. 

INTRODUCTORY. 
CHAPTER PAGE 
MER UMTOCUCLION ce scs sec sess ss cue. srisiewaspreweceneec epacaseine se ck 
MNES A ED PRLTELS ately a's 5 31 ste nee 02d» 0.0 0 4" alee loare se steele visits ea cimateis ve sists ane 
Pipeerteiituinary Examination.....0.. 0.00 noe bane Sabena s eke ca 
Puemnoparatus and Operations. .. .. eles. s sess cee Rrela' ti wia vate x tesescones 4Q 
OAS EDS. s os occa ee cs esse esccees SWieiteae aden ou Coss cesie green hy ere, OO 

PART II. 

DETERMINATIONS. 
TOA te ee ccrac'cs <'s.c%e bee's bas «0 ese a ean a brateraote cis tie Cate en eeey 2 
Ce he) ar eile ae a He, bes Bae ae en SE eat ae eistvfeisteie si tecoe aiieene 100 
PEER OCR OUUG rales a 0 0s a's cee sce te oe ei entre watahe curs php oye PhP Rocks ye 100 
PMO TE ete ee cl olii' clals cle u1s'c)e/e da «)e s'eie vedas alee s'e's cen w shee Sere - 106 
1 ES a) soo FeCl So Re PERF SER EEE BRIER Aor One ee de 
em ALOT: Mente 2s sb die = «\6 Pilots dita alee wiaistarn ore a oe oat Se «sieeve eee) Sa 119 
RPA TAMEOUVCT coca ss 's'cis s vc-c act's since sl semele rarer cin atl ee 
aA ee WECECTINV 5's 2.01 5 = 8S oP TEST on mage bisiaiolespeitiatecs as) atendcecate si stc'a ae - 133 
PLA oie 5's) vie 0 ie neh Rares io cea siege ale aiele ats sche cyehe’gin wih aie a 6 eel oo 
PM CTI ete elena o's 5 re! a isis wits 0. ase. nies: = 6)eid eine sas bse als Bio ws ele pietalma ening ou 144 
XI. Antimony........ Paie ax pieielel eteicla usta tars s'etehalniaeline’ ets sate ava taraie onetelsielnts . 147 
IEP cise ss issa tess © Seemed Sao Wavews aleve ure ar aie ne tates I51 
ees VOTE PN ho, Oye ses bicha 9, aie = © 4 0.0 ace a¥nlswies dia ePea'e Gene's ae. oc-4 a ata ie 154 
XIV. Bismuth..... Dieta eroticy Wik dhéia tr vein covnctie’s otaieis Wine wa eletitg edie waeloys treats - 163 
Py US AGIINI nace oe es + sia. uw, bse tohstal shel slalisiodetate ataMtcatorss: Gist s .stend ets » 166 
PVM POTN Eg feo ecacc'< pee sitvep esis a4 encore Seteieteiays Dod a oralaicer de betete rane _ 168 
XVII. Aluminiums........0. A eee Save dlpiaiecels cielo e wighe ws etree Mearets ones 181 
DOME SA SREOUNUIs 0's 0460 0c ce c0000ss 05006 esn sieges cess ses 'ccwes scp tes crs 188 
MMII SCAU TIN a's ade ol es.ce o's \0.0.6 ¢ e166 em sult sia Viale eels ss eiaidiele uueataubiclcress . IgG 
AP ATICGC Ls cis scence cos ntsucies’s eeu ce dl ous Prete eta ee an ieee 194 


Vill CONTENTS. 
CHAPTER PAG 
ROT PZ eae eas ee eae oe re oa OO lee Ace im gine eT 
XXII Nickeliand Cobalt... s/s ss'va te %s'e © 0 ares se 6s 05 oie eee en 211 
MOLT Caletu nye io. ae ccke sine id cieee o wanes u'« pig'elessc cele kaise nen an 215 
ARXIV. Magnesttm (0.05 6. Dies cae ees oe by ewan hbo ss py 8 oe 220 
POV (DALIT oie, 4 sie's 610 so aa lela a 0 8 ng ealoce soe atu 30 0 ean Pe ey 
XXVI. Sodium and Potassium........... Phatehehets sa Pewee ee 
PAR TSIM. 
SPECIAL ASSAYS AND ANALYSES. 
I. (Assay of Base Bullion. ise ess celey tne ete ee ceseee ss aus 2ge 
II, Assay of Silver Bullion i255 vie 00 e's at ss 0 0 :n 0 aie oleae 236 
IIT... Assay of Gold Bullion: cc s.0 ois oe a nao ts qe see ee ee nen 246 
IV. Special Method for the Assay of Copper Matte, etes. 222. ..u seuss 250 
V, Assay of Silver Sulphides i. 0), < 55 <<... «40 s/s) es ieee 252 
Vy. Chlorination-assay of Silver-Ores..\.% 4.70 ...5 a0 ae alo ete 254 
VI]. Chlorination-assay. of Gold Ores: 0.25228 "a ge ee cnapare eee 256 
VIII. Assay of Gold and Silver Ores containing Metallic Scales.......... 258 
IX; Amalpamation-assay-. Je. oat ee aig #0) een yee SR peel ae 260 
X. Analysis of Coal and Coke...) s.. 25s). acleis nue ee as sae 
XI. Analysis of Gases... cic. 2's oes ejects cle) seine) ages aie 269 
XIT. Analysis of Water... 005 3.05.68 W a's @ ences ve 0 Gane en it epee 
XIII. Acidimetry and Alkalimetry... «0... 22. +. 2 +: on eee 282 
XIV. Chlorimetry. . 05.0 266 2-0 6 ene antes © oe ole he yon 289 
XV. Analysis of White Lead. 2... oo. hci is wo ane alte cee 29g! 
XVI. Specific-gravity Determinations... .. ..... 555 s1ns = ene 293 
XVIT. Analysis of Commercial Aluminium, ........°54 6s yee 298 
XVIII. Analysis of Natural Phosphates, ...... . ...% cae smears sane 300 
XIX. Analysis of Copper and Lead Slags. ..... < .aisenten ralerstare onene s pgOg 
XX. Assay of Gold-Alloys containing Silver and Platinum........... 31la 
PARTLY. 
CALCULATIONS, 

“of. Writing of Chemical Equations.22.29s 16s. eaaene eal» abe mip wie'y aetna mae 
II. Stoichiometry « « . 0s) + s/0s'eeais Ge lelsiaie cps a btn cel pean eee 321 
III. The Calculation of Lead Blast-furnace Charges.............. Je alas eee 
TRART ES. Coscletc wiste a eels ais ba ah Cree pietereene woh Wi kteere te te eates 0 tha 6 olin Je 0 mee 353 
APPENDIX A. Melting and Refining Gold Bullion... sissies sea eae ee 371 
eS B. The Preparation of Pure Gold and Silvery ai. sh eee 382 
aS C. Losses of Gold and Silver in the Fire-dssay.c2).ae ae een 386 

D. Laboratory Tests in Connection with the Extraction of Gold 
by the Cyanide Process «0... . 55%). = sw gmieisie tps eee 40r 
a E. The Analysis of Refined Copper... 2... sss tineem eenienieenre 412 
ee F. The Mechanical Assay of Gold and Silver Ores ..........+ 417 
ae G. The Calculation of Copper-matte Blast-furnace Charges.... 428 


eeesee@eeeetmeoee#e ae eee 8 @eeeeasd eeeeceeoe ee eeeeeeoneeaeeceeeeseeeeaseeeeeeae teas 443 


A MANUAL OF PRACTICAL ASSAYING. 


CHAPTER I. 
INTRODUCTION. 


ASSAYING as practised in the United States, and particu- 
larly as practised in the Far West, may be said to include all 
those operations of analytical chemistry which have for their 
object the determination of the value of ores and metallur- 
gical products. Results are obtained by the following three 
methods: Ist. Fire-assay (dry method); 2d. Gravimetric 
analysis in the wet way; 3d. Volumetric analysis in the wet 
way. In this classification the colorimetric methods are 
included in the division of volumetric analysis. 

Fire-assay determinations involve the separation at the 
metal sought from the other constituents of the ore by the aid 
of heat and suitable fluxes, and its estimation by weighing in a 
state of purity. For example, if the object is the determina- 
tion of lead in an ore, the ore is mixed in a crucible with suit- 
able fluxes and fused. The lead is reduced to the metallic 
state, in which condition it is readily detached from the slag for 
weighing. : 

Gravimetric determinations involve the separation of the 
substance from the other constituents of the ore, and its esti- 
mation by weighing either the substance itself in a state of 
purity or as a constituent of a chemical compound whose com- 


2 A MANUAL OF PRACTICAL ASSAYING. 


position is accurately known. For example, if the object is 
the determination of lime in a mineral, the latter may be 
treated in such a manner that the ultimate product of such 
treatment is pure lime, which can be weighed direct; or the 
treatment may be such that the product is calcium sulphate, 
whose weight may be determined, and as this salt is of invari- 
ble composition the contained lime can readily be calculated. 

Volumetric determinations are those which involve the 
separation of the substance to be determined from all inter. 
fering constituents of the ore, and the final measuring of the 
quantity of a solution necessary to complete a certain re- 
action; or, as in the case of colorimetric determinations, by 
measuring the color imparted to a definite quantity of the 
liquid by the constituent sought in comparison with the color 
imparted to the same quantity of water, or other suitable fluid, 
by a known quantity of the constituent sought. For example, 
if the object is the determination of iron in an iron ore, as the 
iron is capable of reduction from the ferric to the ferrous state, 
and of subsequent oxidation to the ferric state by the addition 
of a suitable oxidizing reagent, if the amount of oxidizing agent 
necessary to just convert the iron to the ferric state is known, 
the amount of iron in the substance can be readily calculated. 
In fire-assaying generally but one constituent of the ore is 

determined in each assay,—except in the case of gold and silver 
determinations, where frequently both the gold and silver are 
determined in the same portion. 

In gravimetric analysis frequently several or all of the con- 
stituents of the substance are determined in the one portion 
taken for analysis. 

In volumetric work generally a separate portion is taken for 
each determination. 

The following hints may be of benefit to the young and in- 
experienced chemist: 

Cleanliness is absolutely essential to good work. 

The work should be systematically arranged and carried 
out. The secret of accomplishing a large amount of work and 
avoiding errors depends largely upon being systematic. The 


INTRODUCTION. a 


apparatus and reagents should be adapted to the work, and 
should be systematically arranged. A system of labelling and 
keeping track of each sample through all stages of the analysis 
should be adopted. By this means mixing of samples will 
be impossible, and a glance will show at any time just how 
far the analysis has proceeded. A good system of labelling 
is to prepare some pieces of heavy paper about one and 
a half inches square. As the substance is weighed out mark 
the number or name of lot, the elements to be determined, and 
weight taken on one of these squares of paper, and carry the 
same along through the course of the analysis with the casse- 
role, beaker, etc., containing the sample, making simple marks 
on the paper from time to time, as necessary, to show the stage 
of the analysis. 

Where much work is to be done do not attempt to carry a 
few determinations through the different stages of the analysis. 
to a finish at once, but start a number of determinations and 
carry them along through the different stages in series, as many 
as convenient at a time. 

Use definite weights in weighing out a substance for analy- 
sis, aS 0.5 or 1.0 gm. 

Do not make up the reagents indiscriminately, but always 
try and have them of a definite strength. In this way the use 
of excessive quantities of reagents will be avoided. The use 
of excessive quantities of reagents not only unnecessarily 
prolongs the operations, but frequently spoils the results, or 
renders it impossible to obtain results. This applies to water 
as well as other reagents. The smallest quantity of a reagent 
which will thoroughly do the work required of it should be 
used. 

In making up standard solutions for volumetric analysis. 
care should be exercised to have them of the proper strength;. 
they should be thoroughly mixed and accurately standardized. 
It is best to have these volumetric solutions of a definite, even 
strength. For example, the potassium-permanganate solution 
used in the determination of iron should be of such a strength 
that each cubic centimetre will equal 5 milligrammes or 10 


4 A, MANTGALSOF PRACTICAL ASSA YING. 


milligrammes of iron. This saves a great deal of time, and 
possibly errors, in the calculation of results. 

Use apparatus which is adapted to the work, and never use 
larger apparatus than is necessary. For example, if 0.5 gm. of 
slag is to be decomposed by acids, if introduced into a large 
casserole a greater quantity of acids will be necessary than if a 
small casserole is used and the operation will be prolonged. 

_ Do not use larger filter-papers than are necessary. A large 
filter requires much more washing than a small one. 

Be careful to avoid loss in boiling and other operations. 

Never accept results where there is reason to believe that 
they may be incorrect, owing to faulty manipulation or acci- 
dents. 


CHAT Pre Rash, 
SAMPLING. 


ALL ores, furnace products, etc., which are to be assayed 
must be first accurately sampled. Accurate sampling is quite 
as essential as accurate assaying; for if the sample does not 
truly represent the lot or mass from which it was taken, the 
subsequent assay will be valueless. 

The assayer or chemist will usually receive the sample 
already prepared; but as he will occasionally be called upon to 
take his own sample, a knowledge of the art of sampling and 
the different methods in vogue is essential. 

The method to be adopted for obtaining a sample will de- 
pend upon the character of the material to be sampled and the 
use to which it is to be put after sampling: for example, in 
the case of a silver ore, whether the ore is high or low grade, 
whether it is wet or dry, etc. If the ore is to be smelted, it is 
not desirable to crush it finer than is necessary to obtain a 
correct sample, as fine ore is undesirable for smelting. If the 
ore is to be milled, fine crushing is not a disadvantage. 

It is hardly necessary to say that in obtaining a sample the 
work should be fairly done, no discrimination as against any 
portion of the lot or mass being allowable. 

There are many other methods of sampling besides those. 
described in the following pages, but the methods as described 
are standard methods, and are in constant use in many of our 
large works, having been tried and found reliable. 

For convenience the subject may be considered under the 
following headings: 

I. Ore sampling. 

2. Sampling of metallurgical products. 


6 A MANUAL OF PRACTICAL ASSA YING. 


Ore Sampling.—A proper sampling requires adequate 
mixing, impartial selection of the sample, and proper relative 
comminution. 

The different methods may be classified as follows: 

1. Hand sampling. 

2. Combined hand and mechanical sampling. 

3. Mechanical sampling. 

The first two methods may be subdivided into— 

Fractional selection (tenth, fifth, etc., of a shovel). 

Quartering (halving, etc.). 

Split shovel (single, double, etc., scoop; assayer’s riffles). 

Channelling (driving one or more channels through a pile; 
driving a scoop or sampling rod through a pile of fine ore, 
etch. 

Mechanical sampling may be subdivided into— 

1. Continuous sampling. 

2. Intermittent sampling. 

A combination of one or more of these methods is fre- 
quently adopted, as taking every tenth shovel from the car, 
crushing this sample, and reducing it by quartering or split 
shovelling. 

Hand sampling consists of taking a sample by hand, the 
only tools necessary being a hammer, mortar, and buckboard. 
Hand or grab samples are frequently taken of the ores, fuels, 
slags, etc., at metallurgical works, as a check and control on the 
metallurgical operations. In taking such samples care should 
be exercised to select the proper relative amount of fine and 
coarse material. The coarse is selected by chipping pieces from 
the large lumps. Having obtained the sample, the whole 
should be further broken to the proper size and then reduced 
by quartering, passing over a split shovel or over assayer’s 
rifles. The final sample should be ground on the buckboard 
until all will pass through an eighty-mesh sieve. At some 
works the practice is to pass all samples through a hundred- 
mesh sieve. The finer the sample is reduced the better. 
Accurate samples can be taken by hand, but to take an accu- 
rate sample of a large lot of ore in this way would involve an 


SAMPLING. 7 


immense amount of labor; hence the second and third methods 
of sampling. 


COMBINED HAND AND MECHANICAL SAMPLING, 


This method of sampling can be carried on in several ways, 
as illustrated by the above classification. Just which method 
will be adopted will depend upon the requirements and the 
facilities in each individual case. Each of the methods gives 
good results, provided the proper precautions are observed. 
The method of fractional selection, followed by comminution 
and then by quartering or split shovelling, is a favorite method 
with many smelting-works, for the following reasons: It is 
desirable that the bulk of the ore as.it is unloaded from the 
‘cars or ore-wagons should pass directly to the smelting beds or 
bins with a minimum amount of handling (most smelting-works 
make no charge for sampling), and alsothat the bulk of the 
ore should remain in as coarse a condition as is consistent with 
proper sampling. 

This method is as follows: As the ore-cars are unloaded 
every tenth, fifth, third, or second shovelful, taken indiscrimi- 
nately, is thrown into a wheelbarrow asa sample. In case the 
lot contains lumps of ore which are too large for the shovel, 
they should be broken with a sledge-hammer as encountered. 
The proportion which will be taken for a sample will depend - 
upon the character of the ore. In the case of a high-grade 
silver or gold ore, ununiform in composition (where the silver 
and gold is unevenly distributed throughout the mass), proper 
sampling will require that the whole lot be taken for sampling. 
In the case of low-grade silver or gold ores, uniform in com- 
position, and lead or copper ores, one tenth of the whole will 
generally give a fair sample. In the case of iron ores, other 
than ores which may be classed as silver and gold ores on 
account of their silver and gold contents, every twentieth or 
less may be taken. In the case of the limestone used as flux 
and the coal and coke, a much smaller proportion may be taken: 
in fact a fair hand sample will generally answer. 


8 A MANUAL OF PRACTICAL ASSAYING, 


The portion taken for a sample is removed to the sampling. 
works and passed through the crusher. Should the sample 
weigh about Io tons, it can now be safely reduced to one ton 
by quartering, except in the case of very high-grade ores, which 
are ununiform in composition. In this latter case, or when 
the sample only weighs about one ton, it should be further 
comminuted to chestnut size by passing it through the rolls. 

The sample can be reduced in bulk by any of the methods. 
classified above, preference generally being given to quartering 
or split-shovelling. If quartering is chosen, the ore as it comes. 
Srom the crusher or rolls is shovelled into a conical pile on the 
sampling-floor, each shovelful being thrown on the apex of the 
cone. When the cone is completed it is flattened out by com- 
mencing at its apex with a shovel and passing the shovel 
around in the path of a spiral until the whole is so flattened 
that it will be from 6 to 12 inches high, and present the appear- 
ance of a flat cake or pie. The point to be observed here is to. 
not disturb the radial distribution of the coarse and fine ore. 
It is now divided into four equal quarters, and two of the 
diagonally opposite quarters removed to one of the bins in the 
sampling-works, where it remains until the lot is sampled and 
settled for. It is convenient to retain an original portion of 
the lot for resampling in case of a dispute between seller and 
buyer on the first sample. The remaining quarters are now 
formed into a conical pile by alternately shovelling from oppo. 
site quarters, each shovelful being thrown on the apex of the 
pile. This cone is flattened and quartered as before, the opera- 
tion being continued until the remaining portion weighs about 
200 pounds, provided the sample has previously been crushed 
to chestnut size. If the ore has not been previously reduced 
to chestnut size it should be so reduced before quartering down 
to 200 pounds. The 200-pound sample should now be further 
comminuted by passing it through a small set of rolls set 
close. It is now further reduced by quartering until it weighs. 
about 5 pounds. This 5-pound sample should now be dried 
on a steam or hot-air bath, and when thoroughly dry is stilk 
further comminuted by passing through a coffee-mill grinder. 


SAMPLING. 9 


The product of the coffee-mill (about 20-mesh) is now reduced 
in bulk on the assaver’s riffle or by quartering until we have a 
sample weighing from I to 3 pounds. This is now ground on 
the buckboard until it will all pass through an 80 or 100 mesh 
sieve. The fine pulp is then spread upon a piece of rubber oil- 
cloth in a thin layer, and the sample bottles or sacks filled by 
taking portions from all over the pile on the point of a steel 
spatula. The bottles are sealed and labelled, the works always 
retaining one sample as an umpire in case of dispute. 

In case the split shovel is adopted the process is essentially. 
the same, except that the ore should be crushed to a size finer 
than is possible in the crusher before using the split shovel. 
The following points are to be observed: The largest particles 





FIG. 2. 


should not be wider than one fourth of the width of the scoop 
used; otherwise when they strike the edges of the scoop they 
may fly out. The scoop should be deep enough to render it 
impossible for pieces striking the bottom to fly out. The 
material should be thrown or delivered on the scoop squarely 
and in a wide flat stream. The split shovel may be one tenth 
‘as wide as the scoop shovel delivering the ore to it, or any other 
width which may be desired. The split shovels are made so as 
to take #,, $, 4, or any desired amount of the ore delivered to 
them, as is shown in the drawings. 

The method of obtaining a sample by channelling is par- 
ticularly adapted to obtaining a sample of a mine dump or a 


10 A MANUAL OF PRACTICAL ASSA VING. 


large pile of ore. It consists in running one or more channels 
or cuts through the pile, taking coarse or fine as it comes. This 
requires that the contents of the pile should have been pretty 
thoroughly mixed before channelling. If such is not the case 
several cuts or channels should be run. After the sample is 
obtained by channelling it should be crushed and cut down as 
described above. Channelling is sometimes adopted in place 
of quartering or split-shovelling after the ore sample has been 
reduced. It answers very well provided the pile is thoroughly 
mixed before channelling each time. Samples of fine ore, such 
as fine concentrates and mill tailings, are frequently obtained by 
driving a scoop or sampling-rod into the pile in several different 
places. The sampling-rod consists of a long steel rod witha 
semicircular depression in one side, being similar to the samp- 
ling rod used by sugar-samplers. 


MECHANICAL SAMPLING. 


A large number of different devices for obtaining samples 
mechanically have been invented. These all depend upon 
taking the sample from a stream of falling ore, a fractional por- 
tion being taken for the sample. The process may be contin- 
uous or intermittent. The main objections to all automatic 
samplers are: The difficulty of getting at the apparatus and 
cleaning it out after each lot is run through. This is a serious 
difficulty with some of the devices, as it will not do to run a 
low-grade galena, low in silver, through the apparatus which 
has just previously sampled a high-grade silver or gold ore, 
unless the apparatus has been previously thoroughly cleaned. 
Another objection is that the ore is not in full view during all - 
stages of the process. Another objection amongst smelters is 
that it requires the whole sample to be crushed to a certain 
degree of fineness before it is run through the sampler. How- 
ever, with proper care automatic samplers give good results, 
and have the great advantage that the work is done mechani- 
cally and indiscriminately. ‘The general scheme with the con- 
tinuous samplers is as follows: The ore is fed into a crusher, 


SAMPLING. II 


from which it passes through rolls. It is then elevated mechani- 
cally to a bin, from which it falls into a long vertical chute, 
where it is again mixed by rods or points in the chute. Ata 
suitable point in the chute some device is introduced to take 
out a fractional portion of the falling stream. The fractional 
portion is frequently passed through a second set of rolls placed 
so as to crush finer than the first set, and again through some 
device, similar to the above, which takes out a fractional por- 
tion. This portion is then passed through a coffee-mill, bucked, 
and treated as before. This process requires that the ore 
should be quite dry before it is run through the mill. This 
method is a favorite one with some smelters for sampling low- 
grade sulphide ores and mattes which are roasted previous to 
smelting. In this case the fineness of the ore is no objection, 
as the ore would have to be reduced to a certain degree of 
fineness before roasting. 

Intermittent samplers take a portion of the ore, fractional 
or otherwise, at intervals. The time between these intervals 
may be controlled mechanically, so that the intervals will be of 
equal duration. Many devices, such as intercepting-buckets, 
which intercept certain quantities at stated intervals, have been 
invented. 

A modification of the method of taking a fractional portion 
from a continuous stream of falling ore has lately been intro- 
duced by The Denver Public Sampling Works which presents 
some advantages. The method as practised by these works is 
essentially as follows: All of the lot, or such fractional portion 
as is deemed necessary, is passed through the crusher and rolls. 
From the rolls it is raised to the upper floor of the mill by an 
elevator, which discharges into an iron hopper which is above 
the floor level and easily accessible for inspection and cleaning. 
This hopper is shown in Fig. 3. 

The bottom of the hopper is connected with a vertical 
chute about 18 inches long, which is closed by a slide-gate (a). 
At the bottom of the chute is a sheet-iron chute (4) which 
diverts a portion of the ore to one side when the gate (qa) is 
opened. Penetrating through this chute is a trough (c) similar 


12 A MANUAL OF PRACTICAL ASSAYING. 


to the scoop of a split shovel, the width of this trough being 
one tenth of the width of the chute. When the gate (q) is 
opened nine tenths of the ore is diverted to one side by the 
chute (4) into a car or wheelbarrow, and one tenth (the sample) 
to the opposite side by the trough (c). This sample is then 
reduced in bulk by split-shovelling to about 200 pounds, which 
is passed through a small set of rolls, after which it is reduced 





T 

I 
by the assayer’s riffle, and is finally ground in the coffee-mill, 
bucked, etc., as before. 

Many devices for the taking of intermittent samples, such 
as intercepting-buckets, which intercept certain quantities at 
stated times, have been invented. One of the best of the 
automatic samplers is that devised by D. W. Brunton, of Aspen, 
Colo.,* which is shown in Fig. 4. This device, in place of 
taking out a portion of the falling stream of ore, diverts the 
whole stream during certain intervals. These intervals may be 
regulated, as required, so as to obtain 10, 20, etc., per cent of 
the ore for a sample by a simple device. As the stream of 
ore is neither split nor divided, fine crushing on large samples 


is entirely unnecessary. After the ore has been crushed it is 
elevated a few feet above the level of the storage-bins and 


Fic. 3. 








* Transactions of the American Institute of Mining Engineers, Vol. XIII, 
p. 639. 


SAMPLING. 13 


discharged into the sampler, Fig. 4, in which C is a vertical 
or inclined chute, containing 
Eae talline stream of ore. £& 
is a funnel for narrowing the 
width of the falling stream, so 
as to reduce to a minimum the 
necessary travel of the deflect- 
Meeecnute A: This chute A is 
pivoted upon a= rock-shaft. 
When it is deflected to the right 
Maereentire stream of ore is 
thrown into A, and when it is 
deflected to the left the entire 
stream is thrown into D. The 
driving-bar J receives its motion 
from the pins Z in the face of the 
driving-wheel 7, which is driven 
by the pulley G. The face of the wheel 7 is perforated by 
two rows of holes, the distance between the two rows being 
the same as the necessary movement of the crank. In these 
holes are inserted a number of pins Z held in place by jam-nuts 
on the interior of the wheel-face. Preferably 20 holes are 
bored in each row, each hole or pin representing 5 per cent 
Mie the time necessary for a complete revolution of thé 
wheel. 

Now, if 50 per cent of the pins are placed in the right-hand 
row of holes, and 50 per cent in the left-hand row, then the 
revolution of the wheel A carrying the pins Z through the 
guides VN on the driving-bar / will hold the deflecting-chute 
A on the right during one half revolution and on the left 
during the other half, thus dividing the stream into two equal 
portions. If 20 percent of the pins are placed in the right- 
hand row and 80 per cent in the left, then the deflecting-chute 
A will be held on the right during one fifth of a revolution and 
on the left during four fifths, thus throwing 20 per cent of the 
Oreinto spout / and 80 percent into spout JD, etc. The ore 
falling into & passes into the storage-bins, whilst the ore falling 











Z 

a> 
leg ) 

TFIID 











Se? [i 
Eliana 





Pa 
al 
ml 











LLLILLLLLL LLL Lf LiL LLL 


S| 
CLL LLL Le 


LO 
To 


Fic. 4. 


14 A MANUAL OF PRACTICAL ASSAYING. 


into D is discharged through a spout into a set of rolls situated 
on the same level as the breaker. 

After being fine-crushed by the rolls, the sample is raised 
by an elevator to the same level as at first, and drops through 
a second divider, similar to the first, set to any desired amount 
per cent. 

The rejected ore falls into the bin with the ore from which 
it was first separated, and the final sample drops into a closed 
and locked bin on the working floor below. 

All of these devices require thorough cleaning after each 
lot is run through and after one lot is finished. Before com- 
mencing ona new lot it is best to run through some of the new 
lot (this portion not to be mixed with the sample) in order to 
thoroughly cleanse the apparatus. 

In handling wet or frozen ore it can generally be cut down 
to about one ton before drying. At this point it is best to dry 
the sample before proceeding further. Before grinding in the 
coffee-mill the sample should be thoroughly dried, the oven 
of an ordinary cook-stove being a very satisfactory piece of 
apparatus for this purpose. 

Dr. S. A. Reed, in The School of Mines Quarterly, Vol. VI, 
No. 4, discusses the subject of ore-sampling mathematically, 
and deduces some interesting formule. 


SAMPLING OF METALLURGICAL PRODUCTS. 


Pig-iron.—The drillings are usually taken from the frac- 
tured end of a pig. In order to protect the sample from slag, 
sand, etc., the end of the pig is covered by wrapping around it 
a piece of heavy paper. As the 
pigs are seldom perfectly homo- 
geneous, especially if the iron con- 
tains much sulphur, phosphorus, or 
manganese, it is best to take several 
drillings, at the points indicated in the sketch, and thoroughly 
mix them together for the sample. 

Base Bullion.—Base or silver-lead bullion, if pure, would 
be an alloy of lead with small quantities of silver and gold. 




























Eg, 





























SAMPLING. ae 


However, it is seldom pure, and may contain copper, zinc, bis- 
muth, arsenic, antimony, sulphur, etc. 

In many of our smelting-works the custom is to ladle directly 
from the lead-well of the blast-furnace into the bullion mould. 
If this method is adopted the resulting bars of bullion will nec- 
essarily contain nearly all the impurities of the lead. At some 
works the practice is to tap the lead-well, or ladle off the lead 
into a cooling kettle. This kettle is of cast-iron, heated under- 
neath by a coal fire, and capable of holding from 600 to 1200 
pounds of lead. When the cooling pot is used the following is 
the method of procedure: From 500 to 1000 pounds of lead is 
tapped or ladled into the cooling pot, which has previously 
been heated, and is kept at a proper temperature by the char- 
coal fire underneath the kettle. The bullion in the kettle is 
stirred and skimmed, the skimmings being returned to the 
blast-furnace, together with the ore charge. This is by far 
the best method of casting, as considerable of the dross of the 
bullion is removed, and the bars are cleaner and more uniform. 
The bullion is cast in moulds of such size that the resulting 
bars of bullion will weigh about 100 pounds. 

It is a well-known fact that if an alloy of lead, silver, and 
gold be cast into a bar the different parts of the bar, owing to 
the sudden chilling, will contain different proportions of silver 
and gold. 

This fact is illustrated by the “ Pattison Process” of de- 
silverization. If the alloy contains zinc, copper, sulphur, etc. 
(any or all of which most bullion contains), the percentage of 
silver and gold in different parts of the bar will vary to a much 
greater extent than in the previous case. The method of 
“zinc desilverization”’ is a partial illustration of this fact. 
These facts render the sampling of the bullion a difficult mat- 
ter if it is at all rich in silver or gold. 

The method of sampling as described below has been 
adopted by many of the large smelting and refining works of 
the United States, and it is believed that it obviates most of 
the difficulties heretofore experienced by smelters and re- 
finers in arriving at a correct sample of the lot of bullion. 


16 A MANUAL OF PRACTICAL ASSAVING. 


The pigs of bullion in series of five are weighed by the 
sampler, the weight being noted and the lot number being 
stamped on each pig as shown in Fig. 5. The pigs are 
unloaded on the sampling platform, as shown in Fig. 5. 

The samples are taken by meams of a steel punch similar 
to a belt punch, but larger, shown in Fig. 6. This punch is 
about 14 inches long, and is made of I-inch to 14-inch steel, so 
arranged that when driven into the bar of bullion it will take 
out a core about #4 inch in diameter and in length equal to half 
the thickness of the bar of bullion. The head-sampler usually 
holds and directs the punch whilst his assistant strikes it with 
a sledge. In order to insure a uniform sample it is essential 
that the punch should be driven half through the bar in each 
case, so that the length of the core should be equal to half the 
thickness of the bar. The samples are taken from each pig at 
a, 0, c, d, ande. The pigs are then turned over, anaes 


Li 












YW 


LU 


ia 


Wj 





LLL 


mm 
ELIZ 





Fiu u. 


Fic, 7. 


samples taken from the bottom side of each pig in the reverse 
order, as shown at f, g,¢, 4, and 7. At some works it is the 
custom to dip the punch in oil, in order to make it drive easier. 
This practice is to be condemned, as dipping in water answers 
the same purpose, and oil greases the cores so that they are 
liable to take up any dirt or particles of dust (which are always 
present in a smelting-works), which are liable to affect the 


SAMPLING. 17 


sample. Oil also makes a bad scum and has a tendency to 
affect the sample in melting. 

A car-load of bullion generally contains 280 pigs. When 
the sampling of the lot is finished the 560 cores are taken to 
the assay office for melting and assay. 

The cores are melted in a clean graphite crucible, which 


- should not be more than two-thirds full when the sample is 


melted down. The melting should be carefully conducted, 
the temperature being gradually raised. It is essential that 
the temperature should be sufficiently high at the last, so that 
the mass will be perfectly fluid; but, on the other hand, the 
temperature should not be raised to such a point that the lead 
will cupel or scorify, as this would result in the loss of lead, 
and consequent enrichment of the sample in silver and gold. 

When the sample is melted and perfectly fluid, the crucible 
is removed from the furnace, its contents thoroughly stirred 
with a clean iron rod, and poured into an iron mould. The 
mould should be of such a size that the resulting bar will be 
about Io inches long, 24 inches wide, and ? inch thick. The 
sample should not be skimmed before pouring, as, if the melt- 
ing is conducted at the proper temperature and not unduly 
prolonged, very little dross will rise upon the surface of the 
lead. When cool, the bar is removed from the mould and 
four samples are cut from it for assay, as shown in Fig. 7. The 
sample bar is stamped with the lot number of the bullion, and 
retained until the lot is settled for. 

In the case of very rich and extremely impure bullion the 
following method may be necessary, although in several years 
experience the author has only had occasion to use this method 
a few times. 

Spectal Method.—When a large amount of dross is formed 
it should be removed by skimming with a perforated skimmer, 
allowing the lead to drain back into the crucible. Place all 
the dross in an iron sample pan and reserve. Now pour the 
clean lead into the mould, and when cool remove the bar and 
weigh it. After weighing, sample the bar by taking four 
samples, as shown above. 


18 A MANUAL OF PRACTICAL ASSA VING. 


Weigh the dross, and, after weighing, break it up on the 
bucking-board and thoroughly sample it, taking four samples. 
of 4 A. T. each, for assay. (For the assay and calculation, see 
Chapter [Part Lil) 

Slags.—Lead and copper furnace slags may be sampled by 
any of the following methods : 

First. After the slag-pot is removed from the furnace it is. 
allowed to cool until a thin crust forms on the top of the slag. 
The crust is broker. and removed with a bar. The end of a 
clean steel bar about one inch in diameter is then plunged into. 
the hot slag to a depth of about three inches and in a few sec- 
onds withdrawn, and the end of the bar with the thin coating 
of slag adhering to it is plunged into water to cool or chill the 
slag quickly. The sample should be brittle and vitreous. 
throughout. If not brittle and vitreous it should be rejected. 
Samples may be taken as frequently as desired, the separate 
samples being bucked down together and passed through a 
100-mesh sieve. 

Second. Some works prefer to take the samples in a small 
ladle as the slag runs from the spout of the furnace. These 
samples are usually taken at stated intervals, and just after the 
furnace has been tapped for matte. They may be poured 
into water from the ladle, in order to make them vitreous and: 
granulated, which facilitates the subsequent pulverization. 

Third. Some works prefer to take the sample from the 
cold cones of slag on the dump. The samples should be taken 
from the centre and above the matte, and about a third way 
from the edge towards the centre. These samples are taken 
with a small hammer, after breaking the cone up with a 
sledge. | 
The first method presents many advantages, as it lessens 
the labor required in pulverizing the sample, and also—at least 
in the case of lead and copper slags—converts the slag into a 
form which is soluble in acids.* 

Silver Bullion.—If the silver is remelted before casting 
into bars, one of the following methods may be adoptes : 


———— 





* Determination of silica, Part II, Chap. I. 


SAMPLING. 19 


Furst. Just before pouring, the contents of the crucible are 
thoroughly stirred with an iron rod. The sample is now taken 
from the centre of the crucible by means of a sampling-cup, 
which consists of a small steel cup provided with a cover which 
fits tight when inserted in the cup. The cup and cover are 
provided with long iron handles. Before using, the cup and 
cover should be heated. The cover is now put on the cup and 
the apparatus inserted into the centre of the molten silver. 
The cover is now withdrawn and the cup allowed to fill with 
silver, when the cover is replaced by means of the handle, the 
apparatus removed from the crucible, and the silver which the 
cup contains poured into water in order to granulate it. 

Second. Just after commencing to pour the silver out of 
the crucible into the moulds some of the silver is caught in a 
small ladle. This operation is repeated when about half the 
silver has been poured, and again when nearly all has been 
poured out. Each of the samples is granulated in water. 

This method of sampling also answers where the silver is 
tapped directly from the cupel furnace into the moulds, a 
sample being taken just after the silver begins to run, another 
when about one half has run out, and a third just before all 
the silver has run out. 

These are about the only methods which are to be recom- 
mended. The taking of a sample from the ends or corners of 
the bar by chipping will not give a fair sample unless the sil- 
ver is very pure, nearly 1000 fine. If the silver has copper or 
other base metal alloyed with it, different portions of the bar 
will vary considerably in their composition. . 

Gold Bullion.—The weighed gold is melted in a graphite 
crucible with suitable fluxes, the slag skimmed off, after which 
it is thoroughly mixed by stirring and poured into a mould. 
Samples are now cut from the top and bottom of the bar. 
These samples should agree in fineness if the work of melting 
has been well done. In the U.S. mints and assay offices the 
practice is to weigh before and after melting, the difference in 
weight being reported as the loss in melting. 

Mattes.—They can be sampled in the same manner as ore. 


20 A MANUAL OF PRACTICAL ASSAYING. 


Automatic sampling answers very well, as the matte has to be 
finely pulverized prior to roasting. 

Flue Dust.—Sampled the same as ore. As it is mostly in 
a fine state, the taking of every tenth shovelful as a sample, 
when cleaning out the flues, answers very well. 

Concentrates.—Concentrates from milling operations are 
sampled in the same manner as ore. Being in a finely pulver- 
ized state, they present no difficulties. 

Tailings. — Tailings from milling operations may be 
sampled the same as concentrates if there is a pile or heap. 
When the tailings are allowed to run into a neighboring 
stream samples should be taken from the tail-box at intervals, 
An automatic device may be arranged for this purpose. 

Silver Precipitate.—The precipitated silver from a leach- 
ing works consists of sulphide of silver mixed with impurities, 
principally sulphides. To obtain a correct sample of this 
material, which runs from 4000 to 14,000 ounces of silver per 
ton, is a difficult matter. The following method answers very 
well, if carefully carried out: Spread the material upon a clean 
iron floor and divide into a number of squares about one foot 
square. From each square take five samples, putting all these 
samples in a pile. The pile should be thoroughly mixed, and 
then spread out and reduced as before. The final sample, of 
about five pounds, should be pulverized in the coffee-mill and 
still further reduced, the final sample being bucked on a buck- 
ing-board until it will all pass through an 80- or 100-mesh 
sieve. 

Copper Ingots.—Pig-copper is usually sampled by drilling 
through the pigs from top to bottom. The top and bottom 
drillings being a mixture of slag and oxides come out as a 
powder, whilst the inside being malleable comes out in the 
form of strings. A good plan is to put the drillings in a glass 
bottle and then operate upon the strings with a pair of scissors 
until the large drillings are all chopped up fine, then quarter. 


Gls WAM EAR ESS 1G Be 
PRELIMINARY EXAMINATION. 


ALL material submitted to the assayer for analysis shoula 
first undergo a preliminary examination, to determine its char- 
acter and principal constituents. A little time spent in this 
manner will frequently result in a great saving of time in the 
subsequent analysis. If the character of the material is not 
understood a wrong method of analysis may be adopted, or a 
substance may be analyzed for some constituent which is pres- 
ent in such small quantities that its determination is unneces- 
sary. Sometimes this preliminary examination is unnecessary, 
as when a substance for analysis is submitted with a statement 
of its character and the constituents required to be deter- 
mined. It frequently happens that the assayer receives a 
substance with the request that its chief constituents be deter- 
mined, in which case a few qualitative tests will generally be a 
sufficient guide. In the case of an ore in lump form, the 
assayer will be able to determine its chief constituents by an 
eye examination and, possibly, a few tests with the blowpipe. 

In most of our metallurgical works the assayer generally 
receives the sample for assay already pulverized. In this case 
the chief constituents and the character of the material can 
generally be determined readily by treating the sample as fol- 
lows: Place about half a gramme of the sample on a large 
watch-glass, and van with a little water, by rotating and gently 
tapping the edge of the glass, so as to separate the lighter 
from the heavier particles. After thus separating the par- 
ticles, an examination with the aid of a magnifying-glass will 
show the principal mineral constituents and their approximate 


amounts. The author has found this an invaluable aid in 
Dy, 


22 A MANUAL OF PRACTICAL ASSAYING, 


determining what the sample should be analyzed for, and also 
the method of analysis to be pursued. For example, the pulver- 
ized sample may show the ore to be oxidized, but upon van- 
ning it will be found to contain small particles of sulphides. 

For the preliminary testing of ores and furnace products 
and the testing of buttons and precipitates the blowpipe is 
extremely valuable. Any intelligent assayer, with a little 
practice, can become sufficiently familiar with the ordinary 
blowpipe tests. 

The following list of blowpipe tests is taken from an article 
by Prof. A. J. Moses,* and gives all of the tests necessary for 
the preliminary examination, by means of the blowpipe, of 
ores, metallurgical products, etc. 


BLOWPIPE TESTS. 


The details in ordinary manipulations, such as obtaining 
beads, flames, coatings, and sublimates, are omitted, and the 
results alone stated. Unusual manipulations are described. 
The bead tests are supposed to be obtained with oxides; the 
other tests are in general true of all compounds not expressly 
excluded. The course to be followed in the case of interfering 
elements is briefly stated. 


Aluminium, Al. 


With Soda.—Swells and forms an infusible compound. 

With Borax or S. Ph.—Clear or cloudy, never opaque. 

With Cobalt Soluttonn—Fine blue when cold. (Certain 
phosphates, borates, and fusible silicates become blue in ab- 
sence of alumina.) 


Ammonia, NH,. 


In Closed Tube.-—Evolution of gas with the characteristic 
odor. -Soda or lime assists the reaction. The gas turns red 
litmus-paper blue, and forms white clouds with HCl vapor. 





* Summary of Useful Tests with the Blowpipe. School of Mines Quar- 
terly, Vol. XI, No. 1. 





PRELIMINARY EXAMINATION. 23 


Antimony, Sb. 


On Coal, R. F.—Volatile white coat, bluish in thin layers, 
continues to form after cessation of blast. (This coat may be 
further tested by S. Ph. or flame.) 

With Bismuth Flux :-—On Plaster.—Orange-red coat, made 
orange by (NH,),S. 

On Coal.—Faint yellow or red coat. | 

In Open Tube.—Dense, white, non-volatile, amorphous sub- 
limate. The sulphide, too rapidly heated, will yield spots of 
red: 

In Closed Tube-—The oxide will yield a white fusible subli- 
mate of needle crystals; the sulphide, a black sublimate, red 
‘when cold. 

Flame.—Pale yellow-green. 

With S. Ph.—Dissolved by O. F., and treated on coal with 
tin in R. F. becomes gray to black. 


Interfering Elements. 


_irsenic—Remove by gentle O. F. on coal. 

Arsenic with Sulphur.—Remove by gently heating in closed 
tube. 

Copper.—The S. Ph. bead with tin in R. F. may be momen- 
tarily red, but will blacken. 

Lead or Bismuth.—Retards formation of their coats by inter- 
mittent blast, or by boracic acid. Confirm coat by flame, not 
By 5. Ph. 


Arsenic, As. 


On Smoked Plaster.—White coat of octahedral crystals. 

On Coal.—Very volatile white coat and strong garlic odor. 
The oxide and sulphide should be mixed with soda. 

With Bismuth Flux :—On Plaster —Reddish-orange coat, 
made yellow by (NH,),». 

On Coal.—Faint-yellow coat. 

In Open Tube.—White sublimate of octahedral crystals. 


24 A MANUAL OF PRACTICAL ASSAYING, 


Too high heat may form brown suboxide or red or yellow 
sulphide. 

In Closed Tube.—May obtain white oxide, yellow or red 
sulphide, or black mirror of metal. 

Flame.—Pale azure-blue. 


Interfering Elements. 


Antimony.—Heat in closed tube with soda and charcoal, 
treat resulting mirror in O. F. for odor. 

Cobalt or Nickel.—F use in O. F. with lead and recognize by 
odor. 

Sulphur.—(a) Red to yellow sublimate of sulphide of arsenic 
in closed tube. 

(6) Odor when fused with soda on coal. 


Barium, Ba. 


On Coal, with Soda.—F uses and sinks into the coal. 

Flame.—Yellowish green, improved by moistening with 
PGi. 

With Borax or S. Ph.—Clear and colorless; can be flamed 
opaque white. 


Bismuth, Bi. 


On Coal.—In either flame is reduced to brittle metal and 
yields a volatile coat, dark orange-yellow hot, lemon-yellow 
cold, with yellowish-white border. 

With Bismuth Flux (sulphur, 2 parts; potassic iodide, 1 
part; potassic bisulphate, 1 part) :—Ox Plaster.—Bright-scarlet 
coat surrounded by chocolate-brown with sometimes a reddish 
border. The brown may be made red by ammonia. (May be 
obtained by heating S. Ph. on the assay.) 

On Coal_—Bright-red coat with sometimes an inner fringe 
of yellow. 

With S. Ph.—Dissolved by O. F. and treated on coal with 
tin in R. F. is colorless hot, but blackish gray and opaque cold. 


PRELIMINARY EXAMINATION. 25 


Interfering Elements. 


Antimony.—Treat on coal with boracic acid, and treat the 
resulting slag on plaster with bismuth flux. 
Lead.— Dissolve coat in S. Ph., as above. 


Boron, B. 


All borates intumesce and fuse to a bead. 

Flame.—Y ellowish green. May be assisted by: (a) Moisten- 
ing with H,SO,; (4) Mixing to paste with water, and boracic- 
acid flux (44 parts KHSO,,1 part CaF); (c) By mixing to 
paste with H,SO, and NH,F. 


Bromine, Br. | 


With S. Ph., saturated with CuO.—Treated at tip of blue 
flame, the bead will be surrounded by greenish-blue flame. 
In Matrass with KHSO,— Brown, choking vapor. 


Interfering Elements. 


Silver.—The bromine melts in KHSO, and forms a blood- 
red globule, which cools yellow and becomes green in the 
sunlight. 


Cadmium, Cd. 


On Coal, R. F.—Dark-brown coat, greenish yellow in thin 
layers. Beyond the coat, at first part of operation, the coal 
shows a variegated tarnish. 

On Smoked Plaster with Bismuth Flux.—White coat made 
orange by (NH,),S. 

With Borax or S. Ph.—O. F. Clear yellow hot, colorless 
cold; can be flamed milk-white. The hot bead touched to 
Na,S,O, becomes yellow. 

R. F. Becomes slowly colorless. 


Interfering Elements. 


Lead, Bismuth, Zinc—Collect the coat, mix with charcoal 
dust, and heat gently in a closed tube. Cadmium will yield 


26 A MANUAL OF PRACTICAL ASSAYING. 


either a reddish-brown ring or a metallic mirror. Before 
collecting coat treat it with O. F. to remove arsenic. 


Calcium, Ca. 


On Coal, with Soda.—Insoluble, and not absorbed by the 
coal. 
Flame.—Y ellowish red, improved by moistening with HCl. 
With Borax or S. Ph.—Clear and colorless, can be flamed 
opaque. 
Carbonic Acid, CO,,. 


With Nitric Acid.—Heat with water and then with dilute 
acid; CO, will be set free with effervescence. The escaping 
gas will render lime-water turbid. 

With Borax or S. Ph—After the flux has been fused toa 
clear bead, the addition of a carbonate will cause effervescence 
during further fusion. 


Chlorine, Cl. 


With S. Ph., saturated with CuO.—Treated at tip of blue 
flame the bead will be surrounded by an intense azure-blue 
flame. 

On Coal, with CuO.—Grind with a drop of H,SO,, spread 
the paste on coal, dry gently in O. F., and treat with blue 
flame, which will be colored greenish blue and then azure-blue. 


Chromium, Cr. 
With Borax or S. Ph.—O. ¥. Reddish hot, fine yellow green 
cold. 
R. F. In borax, green hot and cold. In S. Ph. red hot, 
green cold. 


With Soda.—O. F. Dark yellow hot, opaque and light yellow 
cold. 


R. F. Opaque and yellowish green cold. 
Interfering Elements. 


Manganese.—The soda bead in O. F. will be bright yellowish 
green. 


PRELIMINARY EXAMINATION. 27 


Cobalt, Co. 


On Coal, R. F.—The oxide becomes magnetic metal. The 
solution in HCl will be rose-red, but on evaporation will be 
blue. 

With Borax or S. Ph.—Pure blue in either flame. 


Interfering Elements. 


Arsentc.—Roast and scorify with successive additions of 
ipotax. Lhere may be, in order given: Yellow (iron), green 
(iron and cobalt), blue (cobalt), reddish brown (nickel), green 
{nickel and copper), blue (copper). 

Copper and other Elements which Color Strongly—F use with 
borax and lead on coalin R. F. The borax on platinum wire 
in O. F. will show the cobalt, except when obscured by much 
iron or chromium. 

Iron, Nickel, or Chromium—Fuse in R. F. with a little — 
metallic arsenic, then treat as an arsenide. 

Sulphur or Selentum—Roast and scorify with borax, as 
before described. 


Copper, Cu. 


On Coal, R. F.—-Formation of red metallic metal. 

Flame.—Emerald-green or azure-blue, according to com- 
pound. The azure-blue flame may be obtained (sulphur, 
selenium, and arsenic should be removed by roasting; lead 
necessitates a gentle heat)— 

(2) By moistening with HCl or aqua regia, drying gently in 
‘O. F.; and heating strongly in R. F.; 

(6) By saturating S. Ph. bead with substance, adding com- 
mon salt, and treating with blue flame. 

With Borax or S. Ph.—O. F. Green hot, blue or greenish 
blue cold. (By repeated slow oxidation and reduction, a borax 
bead becomes ruby-red.) 

R. F. Greenish or colorless hot, opaque and yeeeuaneih red 
cold. With tin on coal this reaction is more delicate. 


28 A MANUAL OF PRACTICAL ASSAYING. 


Interfering Elements. 


General Method.—Roast thoroughly, treat with borax on 
coal in strong R. F. (oxides, sulphides, sulphates, are best 
reduced by a mixture of soda and borax), and— 

If Button Forms.—Separate the button from the slag, re- 
move any lead from it by O. F., and make either S. Ph. or 
flame test upon residual button. 

If No Visible Button Forms.—Add test lead to the borax 
fusion, continue the reduction, separate the button, ana treat 
as in next test (lead alloy). 

Lead or Bismuth Alloys—Treat with frequently changed 
boracic acid in strong R. F., noting the appearance of slag and 
residual button. 

Trace.—A red spot in the slag. 

Over One Per Cent.—The residual button will be bluish 
green; when melted will dissolve in the slag and color it red 
upon application of the O. F., or may be removed from the 
slag and be submitted to either the S. Ph. or the flame test. 


Fluorine, F. 


Etching Test.—lf fluorine be released it will corrode glass 
in cloudy patches, and in presence of silica there will be a 
deposit on the glass. According to the refractoriness of the 
compound the fluorine may be released— 

(a) In closed tube by heat ; 

(2) In closed tube by heat and KHSO, ; 

(c) In open tube by heat and glass of S. Ph. 

With Conc. H,SO, and SiO,—Ilf heated, and the fumes 
condensed by a drop of water upon a platinum wire, a film of 
silicic acid will form upon the water. 


Iodine, I. 


With S. Ph., saturated with CuO.—Treated at the tip of the 
blue flame, the bead is surrounded by an intense emerald-green 
flame. 


PRELIMINARY EXAMINATION. 29 


In Matrass with KHSO,.—Violet, choking vapor and brown 
sublimate. 

In Open Tube, with equal parts Bismuth Oxide, Sulphur, 
and Soda.—A brick-red sublimate. 

With Starch Paper.—The vapor turns the paper dark purple 


Inter fering Elements. 


Stlver.—The iodide melts in KHSO, to a dark-red globule, 
yellow on cooling, and unchanged by sunlight. 


Iron, Fe. 


On Coal—R. F. Many compounds become magnetic. 
Soda assists the reaction. 

With Borax.—O. F. Yellow to red hot, colorless to yellow 
cold. (A slight yellow color can only be attributed to iron 
when there is no decided color produced by either flame in 
highly-charged beads of borax and S. Ph.) 

R. F. Bottle-green. With tin on coal, violet-green. 

With S. Ph.—O. F. Yellow to red hot, greenish when cool- 
ing. Colorless to yellow cold. 

R. F. Red hot and cold, greenish while cooling. 

State of the Iron.—A borax-blue bead from CuO is made 
red by FeO and greenish by Fe,Q,. 


Interfering Elements. 


Chromium.—Fuse with nitrate and carbonate of soda on 
platinum, dissolve in water, and test residue for iron. 

Cobalt.—By dilution the blue of cobalt in borax may often 
be lost before the yellow of iron. 

Copper.—May be removed from borax bead by fusion with 
lead on coal in R. F. 

Manganese.—(a) May be faded from borax bead by treat- 
ment with tin on coal in R. F.; 

(6) .May be faded from S. Ph. bead by R. F. 

Nickel_——May be faded from borax bead by R. F. 


30 A MANUAL OF PRACTICAL ASSA YING. 


Tungsten or Titantum.—The S. Ph. bead in R. F. will be 
reddish brown instead of blue or violet. 

Uranium.—As with chromium. 

Alloys, Sulphides, Arsenides, etc.—Roast, treat with borax 
on coal in R. F., then treat borax in R. F. to remove reducible 
metals. 


Lead, Pb. 


On Coal.—In either flame is reduced to malleable metal, 
and yields near the assay a dark lemon-yellow coat, sulphur- 
yellow cold, and bluish white at border. (The phosphate 
yields no coat without the aid of a flux.) 

With Bismuth Flux :—On FPlaster.—Chrome-yellow coat, 
blackened by (NH,),S. 

On Coal.—V olatile yellow coat, darker hot. 

Flame.—Azure-blue. 

With Borax or S. Ph.—O. F. Yellow hot, colorless cold. 
Flames opaque yellow. 

R. F. Borax bead becomes clear, S.Ph. bead cloudy. 


Interfering Elements. 


Antimony.—Treat on coal with boracic acid, and treat the 
resulting slag on plaster with bismuth flux. 

Arsenic Sulphide—Remove by gentle O. F. 

Cadmium.— Remove by R. F. 

Bismuth.—Usually the bismuth-flux tests on plaster are 
sufficient. In addition the lead coat should color the R. F. 
blue. 


Lithium, Li. 


Flame.—Crimson, best obtained by gently heating near the 
wick. 


Interfering Elements. 


Sodium.—(a) Use a gentle flame and heat near the wick: 
(6) Fuse on platinum wire with baric chloride in O. F. The 


PRELIMINARY EXAMINATION. 31 


flame will be first strong yellow, then green, and, lastly, 
crimson. 

Calcium or Strontium.—As these elements do not color the 
flame in the presence of baric chloride, the above test will 
answer. 

Szlicon.—Make into a paste with boracic-acid flux and 
water, and fuse in the blue flame. Just after the flux fuses the 
red flame will appear. 


Magnesium, Mg. 


On Coal, with Soda.—Insoluble, and not absorbed by the 
coal. 

With Borax or S. Ph.—Clear and colorless; can be flamed 
opaque-white. 

With Cobalt Solution. ie aely heated, becomes a pale- 
flesh color. (With silicates this action is of use only in the 
absence of coloring oxides. The phosphate, arsenate, and 
borate become violet-red.) 


Manganese, Mn. 


With Borax or S. Ph.—O. F. Amethystine hot, reddens on 
cooling. With much, is black and opaque. (The colors are 
more intense with borax than with S. Ph.) If a hot bead is 
touched to a crystal of sodic nitrate an amethystine or rose- 
colored froth is formed. 

R. F. Colorless or with black spots. 

With Soda.—O. F. Bluish green and opaque when cold. 
Sodic nitrate assists the reaction. 


L[uterfering Elements. 


Chromium.—The soda bead in O. F. will be bright yellow- 
ish green instead of bluish green. 
Stlicon.—Dissolve in borax, then make soda fusion. 


32 A MANUAL OF PRACTICAL ASSAYING, 


Mercury, Hg. 


With Bismuth Flux :—On Plaster.—Volatile yellow and 
scarlet coat. If too strongly heated the coat is black and 
yellow. 

On Coal.—Faint-yellow coat at a distance. 

In Matrass, with Dry Soda or with Litharge.—Miuirror-like 
sublimate, which may be collected in globules. (Gold-leaf is 
whitened by the slightest trace of vapor of mercury.) 


Molybdenum, Mo. 


On Coal.—O. F. A coat yellowish hot, white cold; crystal- 
line near assay. 

Rk. F. The coat is turned in part deep blue, in part dark 
copper-red. 

Flame.—Y ellowish green. 

With Borax.—O. F. Yellow hot, colorless cold. 

R. F. Brown to black and opaque. 

With S. Ph.—O. F. Yellowish green hot, eulomeg: cold. 
(Crushed between damp unglazed paper becomes red, brown, 
purple, or blue, according to amount present.) 

R. F. Emerald-green. 

Dilute (+) HCl Solutions.—If insoluble, the substance may 
first be fused with S. Ph. in O. F. Then, if dissolved in the 
acid and heated with metallic tin, zinc, or copper, the solutions ' 
will be successively blue, green, and brown. If the S.Ph. bead 
has been treated in R. F. the solution will become brown. 


Nickel, Ni. 


On Coal, R. F.— The oxide becomes magnetic. 

With Borax.—O. F. Violet hot, pale reddish brown cold. 

R. F. Cloudy, and finally clear and colorless. 

With S. Ph.—O. F. Red hot, yellow cold. 

R. F. Red hot, yellow cold. On coal with tin becomes 
colorless. 


PRELIMINARY EXAMINATION. 33 


Interfering Elements. 


General Method.—Saturate two or three borax beads with 
roasted substance, and treat on coal with strong R. F. Ifa 
visible button results, separate it from the borax and treat 
Smee ietnthe ©. 1. replacing the S. Ph. when a color is 
obtained. If no visible button results, add either a small gold 
button or a few grains of test-lead. Continue the reduction, 
and— 

With Gold.—Treat the gold alloy on coal with S. Ph. in 
strong O. F. 

With Lead.—Scorify button with boracic acid to small size, 
‘complete the removal of lead by O. F. on coal, and treat 
residual button with S. Ph. in O. F. 

Arsenic.— Roast thoroughly, treat with borax in R. F. as 
long as it shows color, treat residual button with S. Ph. in 
mul: 

Alloys —Roast and melt with frequently changed borax in 
kK. F., adding a little lead if infusible. When the borax is no 
longer colored, treat the residual button with S. Ph. in O. F. 


Nitric Acid, HNO,,. 
In Matrass with KHSO,, or in Closed Tube with Litharge. 


—Brown fumes with characteristic odor. The fumes will turn 
ferrous-sulphate paper brown. 


Phosphorus, P. 


Flame.—Greenish blue, momentary. Improved by cone. 
‘c\ 0 Fea 

In Closed Tube with Dry Soda and Magnestum.—The soda 
and substance are mixed in equal parts and dried, and made 
to cover the magnesium. Upon strongly heating there will be 
a vivid incandescence, and the resulting mass, crushed and 
moistened, will yield the odor of phosphuretted hydrogen. 


Potassium, K. 


Flame.—Violet, except borates and phosphates. 


34 A MANUAL OF PRACTICAL ASSAYING. 


Interfering Elements. 


Sodium.—(a) The flame through blue glass will be violet or 
blue ; 

(6) A bead of borax and a little boracic acid made brown 
by nickel will become blue on addition of a potassium com- 
pound. 

Lithium.—The flame through green glass will be bluish 
ereen. 


Selenium, Se. 


On Coal, R. F.—Disagreeable horse-radish odor, brown 
fumes, and a volatile steel-gray coat with a red border. 

In Open Tube.— Steel-gray sublimate with red border, 
sometimes white crystals. 

In Closed Tube.—Dark-red sublimate and horse- radied odor. 

Flame.—Azure-blue. 

On Coal, with Soda.—Thoroughly fuse in R. F., place on 
' bright silver, moisten, crush, and let stand. The silver will be 
blackened. 


Silicon, Si. 

On Coal, with Soda.—With its own volume of soda, dis- 
solves with effervescence to a clear bead. With more soda 
the bead is opaque. 

With Borax.—Clear and colorless. 

With S. Ph.—Insoluble. The test made upon a small 
fragment will usually show a translucent mass of undissolved 
matter of the shape of the original fragment. 

When not decomposed by S. Ph., dissolve in borax nearly — 
to saturation, add S. Ph., and re-heat for a moment. The 
bead will become milky or opaque-white. 


Silver, Ag. 


On Coal.—Reduction to malleable white metal. 
With Borax or S. Ph.—O. F. Opalescent. 
Cupellation.—F use on coal with one volume of borax-glass 


_" *—- a 


PRELIMINARY EXAMINATION. a0 


and one to two volumes of test-lead in R. F. for about two 
minutes. Remove button and scorify it in R. F. with fresh 
borax, then place button on cupel and blow O. F. across it, 
using as strong blast and as little flame as are consistent with 
keeping button melted. 

iieiiesitnarce: is dark, or if the button freezes before 
brightening, or if it brightens but is not spherical, rescorify it 
on coal with borax, add more test-lead, and again cupel, until 
there remains only a white spherical button of silver. 


Sodium, Na. 
Flame.—Reddish yellow. 


Strontium, Sr. 


On Coal, with Soda.—Insoluble, absorbed by the coal. 

Flame.—Intense crimson, improved by moistening with 
Cl. 

With Borax or S. Ph.—Clear and colorless; can be flamed 
opaque. 


Interfering Elements. 


Baritum.—The red flame may show upon first introduction 
of the sample into the flame, but it is afterwards turned brown- 
ish yellow. 

Lithtum.—Fuse with baric chloride, by which the lithium 
flame is unchanged. 


Sulphur, S. 


On Coal, with Soda and a little Borax.—Thoroughly fuse in 
the R. F. flame, and either, 

(a) Place on bright silver, moisten, crush, and let stand. 
The silver will become brown or black. Or, 

(6) Heat with dilute HCl (sometimes with powdered zinc); 
the odor of H,S will be observed. 

In Open Tube—Suffocating fumes. Some sulphates are 
unaffected. 


36 A MANUAL OF PRACTICAL ASSAYING, 


In Closed Tube.—May have sublimate red when hot, yellow 
cold, or sublimate of undecomposed sulphide, or the substance 
may be unaffected. 

With Soda and Stlica (equal parts).—A yellow or red bead. 

To Determine whether Sulphide or Sulphate-—Fuse with 
soda on platinum foil. The sulphide only will stain silver. 


Tellurium, Te. 


On Coal—vVolatile white coat with red or yellow border. 
If the fumes are caught on porcelain, the resulting gray or 
brown film may be turned crimson when moistened with cone. 
H,SO,, and gently heated. 

On Coal, with Soda.—Thoroughly fuse in R. F. Place on 
bright silver, moisten, crush, and let stand. The silver will be 
blackened. 

Flame.—Green. 

In Open Tube.—Gray sublimate fusible to clear drops. 

With H,SO, (conc.).—Boiled a moment, there results a pur- 
ple-violet solution, which loses color on further heating or on 
dilution. 


Tin, Sn. 


On Coal.—O. F. The oxide becomes yellow and lumi‘ous. 

R. F. A slight coat, assisted by additions of sulphur or soda. 

With Cobalt Solution.—-Moisten the coal in front of the 
assay, with the solution, and blow a strong R. F. upon the 
assay. The coat will be bluish green when cold. 

With CuO wn Borax Bead.—A faint-blue bead is made 
reddish brown or ruby-red by heating a moment in R. F. with. 
a tin compound. 


Interfering Elements, 


Lead or Bismuth Alloys.—It is fair proof of tin if such an 
alloy oxidizes rapidly with sprouting and cannot be kept fused. 

Zinc.—On coal with soda, borax, and charcoal in R. F., the 
tin will be reduced, the zinc volatilized; the tin may then be 
washed from the fused mass. 


PRELIMINARY EXAMINATION, RY A 


Titanium, Ti. 

With Borax.—O. F. Colorless to yellow hot, colorless cold, 
opalescent or opaque white by flaming. » 

R. F. Yellow to brown, enamel-blue by flaming. 

With Ph. SO. F. as with borax. 

R. F. yellow hot, violet cold. 

HCl Solutions.—If insoluble, the substance may first be 
fused with S. Ph. or with soda, and reduced. If then dissolved 
in dilute acid and heated with metallic tin, the solution will 
become violet after standing. Usually there will also bea turbid 
violet precipitate, which becomes white. 


Interfering Elements. 


Iron.—The S. Ph. bead in R. F. is yellow hot, brownish 
red cold. 


Tungsten, W. 


With Borax.—O. F. Flame colorless to yellow hot, colorless 
cold; can be flamed opaque white. 

R. F. Colorless to yellow hot, yellowish brown cold. 

With S. Ph.—O. F. Clear and colorless. 

R. F. Greenish hot, blue cold. On long blowing or with 
tin on coal becomes dark green. 

With Dilute HCl—If insoluble, the substance may first be 
fused with S. Ph. The solution heated with tin becomes dark 
blue; with zinc it becomes purple and then reddish brown. 


Interfering Elements. 
Iron.—The S. Ph. in R. F. is yellow hot, blood-red cold. 


Uranium, U. 


With Borax.—O. F. Yellow hot, colorless cold; can be 
flamed enamel-yellow. 
Rk. F. Bottle-green ; can be flamed black, but not enamelled. 


38 A MANUAL OF PRACTICAL ASSAYING. 


With S. Ph.—O. F. Yellow hot, yellowish green cold. 
R. F. Emerald-green. 


Interfering Elements. 
Jron.—With S. Ph. in R. F. is green hot, red cold. 


Vanadium, V. 


With Borax.—O. F. Colorless or yellow hot, greenish-yek 
low cold. © ; 

R. F. Brownish hot, emerald-green gold. 

With S. Ph.—O. F. Dark yellow hot, light yellow cold. 

R. F. Brown hot, emerald-green cold. 

H,SO, Solutions.—Reduced by zinc becomes successively 
yellow, green, bluish-green, blue, greenish-blue, bluish-violet, 
and lavender. 


Zinc, Zn. 


On Coal.—O. F. The oxide becomes yellow and luminous. 

R. F. Yellow coat, white when cold, assisted by soda and 
a little borax. 

With Cobalt Solution—Moisten the coal in front of the 
assay, with the solution, and blow a strong R. F. upon the 
assay. The coat will be bright yellow-green when cold. 


Interfering Elements. 


Antimony.—Remove by strong O. F., or by heating with 
sulphur in closed tube. 

Cadmium, Lead, or Bismuth.—The combined coats will not 
prevent the cobalt-solution test. 

Tin.—The coats heated in an open tube, with charcoal dust 
by the O. F., may yield white sublimate of zinc. 


QUALITATIVE TESTS. 


Th 2 following summary of characteristic qualitative tests in 
the wet way will be found useful in the preliminary examina- 
tion of ores, furnace products, etc. : 


PRELIMINARY EXAMINATION. 39 


Aluminium, Al. 


1. Alkali hydroxides precipitate grayish-white, Al(HO),, 
soluble in fixed alkali-hydroxides, but only slightly soluble in 
NH,OH if NH,Cl is present. 

2. Basic acetate of aluminium is precipitated by addition of 
NaC,H,O, to a warm and slightly acid solution. 

Conjfirm.—By blowpipe test. 


Antimony, Sb. 


1. H,S precipitates orange-red Sb,S, from acid solutions. 
‘The precipitate is soluble in HCl, in alkalies, and in alkaline 
sulphides. 

2. H,S precipitates orange Sb,S, from acid solutions. The 
precipitate is soluble in HCl, in alkalies, and alkaline sulphides, 

To distinguish between Sb,O, and Sb,O,, add solution of 
AgNO,, in the presence of KOH or NaOH. S0,0O, precipi- 
tates black, Ag,O, which is insoluble in NH,OH; and $4,0, 
precipitates whzte, AgSbO,, which is soluble in NH,OH. 


Arsenic, As. 


1. H,S precipitates yellow As,S, best from HCl solutions. 
Soluble in alkalies and alkaline sulphides, insoluble in HCl. 

2. H,S precipitates yellow, As,S, from acid solutions after 
heating solution and passing gas for some time. 

3. AgNO, precipitates yellow Ag,AsO, or reddish-brown 
Ag,AsO,, soluble in- dilute acids, ammonia, and ammonia salts. 

4. CuSO, precipitates yellowtsh-green Cu,(AsO,), or green- 
ash-blue, CuHAsO,, soluble in NH,OH and NH,Cl. 

5. Ammonium magnesia mixture precipitates whzte MgNH, 


AsO,. 


Barium, Ba. 


1. Alkali carbonates precipitate zwhzte BaCO, soluble in 
HCl and HNO,. Soluble in acids. 


40 A MANUAL OF PRACTICAL ASSAYING. 


2. Soluble sulphates and H,SO, precipitate whzte BaSO,, 
which is practically insoluble in acids and water. 
Conjirm.—By blowpipe test. 


Bismuth, Bi. 


1. H,S or (NH,),S precipitates brownish-black Bi,S, insolu- 
ble in dilute acids, but soluble in strong HNO,. 

2. H,O precipitates from the chloride whzte BiOCl, in-. 
soluble in an excess, but soluble in HCl and HNO,. 

3. SnCl, in the presence of NaOH or KOH precipitates. 
black Bi,O,. 

Conjfirm.—By blowpipe test. 


Bromine, Br. 


1. AgNO, precipitates yellowish-white AgBr; changes to: 
gray, soluble in KCN, slightly soluble in NH,OH, insoluble in 
HNO,. 

Separation of Cl, Br, and [—Place a solution of the mixture 
in a test-tube with a little MnO, and water, add a drop of dilute: 
H,SO, (one in ten). A brown color indicates I. Boil; violet: 
vapors are given off. When these cease add 2 cc. of H,SO, 
and boil; drown vapors indicate Br. Boil until brown vapors. 
cease and cool. When cold, add an equal volume of H,SO, 
and heat; green vapors indicate Cl. 


Boron, B. 
I. BaCl, and CaCl, precipitate whzte Ba,(BO,), and Ca,(BO, Jer 
2. AgNO, precipitates white Ag,BO,. 
3. Free boracic acid turns turmeric paper brownish red, 
becoming more intense when the paper is dried. When mixed: 
with HCl to acid reaction and dried it becomes ved. 


Cadmium, Cd. 


pol hisy care (NHS precipitates yellow CdS, insoluble in 
sti acids, alkalies, alkali sulphides, or cyanides. Soluble in 
strong hot HCl, HNO,, and H,SOQO,. 


PRELIMINARY EXAMINATION. AI 


2. Zn precipitates from acid and ammoniacal solutions 
gray Cd. 

3. KOH and NaOH precipitate wzte Cd(OH),, insoluble 
in excess; whilst NH,OH precipitate whzte Cd(OH),, which is 
soluble in excess. 

Confirm.—By blowpipe test. 


Calcium, Ca. 


} 1. H,SO, precipitates whzte CaSO,, soluble in a concentrated 
solution of (NH,),SO,; distinction from Ba and Sr. 

2. Alkaline arseniates precipitate CaHAsO,, soluble in acids 
and NH,OH. Ba, Sr, and Mg give this precipitate only in 
concentrated solutions. Ammonia salts must be absent. 

Confirm.—By blowpipe test. 


Carbonic Acid, CO,,. 
1. Add HNO, to substance in a test-tube, and pass gas 
through a solution of lime-water. A white precipitate of CaCQ, 
indicates CO.,,. 


Chlorine, Cl. 
1. AgNO, precipitates whzte AgCl, soluble in NH,OH. 


Chromium, Cr. 
1. NH,OH precipitates bluish green Cr(OH),, slightly 


soluble in excess. 

2. From solutions of CrO, lead salts precipitate yellow: 
PbCrO,, soluble in HNO, and insoluble in acetic acid. Diffi- 
cultly soluble in KOH. 

3. A very delicate test for Cr as CrO, is by means of H,O, 
(hydrogen peroxide) and ether, giving a fine d/ue color. 


Cobalt, Co. 


1. Fixed alkalies precipitate blue basic salts. This precipi- 
tate absorbs oxygen and becomes olive-green hydroxide. If 


42 A MANUAL OF PRACTICAL ASSA YING. 


boiled before oxidation in the air becomes vose-red Co(OH), ; 
does not dissolve in excess. HN,OH produces the same 
precipitate, which is soluble in excess. 

2. K,FeC,N, precipitates dark brown Co (FeC, N,),, insolu- 
ble in HCl. If to a solution of Co or Ni an excess of NH,Cl 
and NH,OH is added and then K,FeC,N,, a blood-red color 
indicates Co. If Ni is present, and the solution is boiled, a 
copper-red precipitate forms; if any Co is present, a dirty green, 
on boiling. 

3. To a dilute solution of cobaltous nitrate add tartaric or 
citric acid, then an excess of ammonia, and a few drops of 
potassium ferricyanide; a deep-red color appears, even if largely 
diluted. 

Conjirm.—By blowpipe test. 


Copper, Cu. 


1. NH,OH produces a deep-blue solution. 

2. NaOH and KOH when added to saturation precipitate 
blue Cu(OH),, insoluble in excess. When boiled the precipi- 
tate changes to black Cu,O,(OH),. Organic substances gens 
erally prevent the formation of this precipitate. 

3. Fe and Zn precipitate metallic copper from cupric 
solutions. 


| Iron, Fe. 
FeO.—1. K,FeC,N, precipitates dark-blue Fe,(FeC,N,),, in- 


soluble in acids. 
2. NH,OH precipitates whzte Fe(OH),. 
Fe,O,.—1. NH,CNS produces a d/o0¢-red solution. 
2. NH,OH precipitates brownish Fe,(OH),. 


Lead, Pb. 


1. Zn precipitates crystals of Pb. 

2. H,SO, precipitates whzte PbSO,, slightly soluble in ex- 
cess, insoluble in alcohol, but soluble in ammonium acetate or 
citrate. 


PRELIMINARY EXAMINATION, 43 


3. H,S or (NH,),S precipitates 4/ack PbS, soluble in HNO, 
with formation of PbSO,,. 
4. K,FeC,N, precipitates whzte Pb,FeC,N,. 


Lithium, Li. 
1. Nitrophenic acid forms a yed/ow precipitate. 
2. Na,CO, precipitates whzte Li,CO,, slightly soluble in 
FO. 
Conjirm.—By blowpipe and spectroscope. 


Magnesium, Mg. 
1. Na,HPO, precipitates, in presence of NH,OH and 
NH,Cl, whzte MgNH,PO,._ Fine crystals. 
Confirm.—By blowpipe. 


Manganese, Mn. 


1. Boil with HNO,, and add peroxide of lead. A reddish- 
violet solution (color of potassium permanganate) indicates Mn. 


Mercury, Hg. 


zt. A piece of bright metallic copper is coated with a 
precipitate of metallic Hg, upon insertion in a solution of Hg. 

2. SnCl, precipitates first whzte Hg,Cl, and then gray Hg. 

To distinguish between mercurous and mercuric compounds 
HCI precipitates whzte Hg,Cl,, soluble in aqua regia, HNO,, and 
NH,Cl, and blackened by NH,OH, from mercurous compounds. 
No precipitate on addition of HCl to mercuric compounds. 


Molybdenum, Mo. 
Upon heating the acid solution with metallic zinc it will turn 
successively blue, green, and brown. 
Confirm.—By blowpipe test. 
Nickel, Ni. 


1. Alkaline carbonates precipitate green basic carbonate 


- 2NiCO,, 3Ni(OH),, soluble in (NH,),CO, or, in excess of re- 


44 A MANUAL OF PRACTICAL ASSAYING, 


agent, with blue or greenish-blue color. Again precipitated by 
KOH or NaOH as pale-green Ni(OH),. 

2. NH,OH in excess gives 6/ue color. 

3. KCN precipitates pale-green NiC,N,, soluble in excess. 
Upon boiling with NaClO, é/ack Ni(OH), is precipitated. 
Distinction from Co, which gives a azrty-white precipitate with 
KCN, soluble in excess, but no precipitate being formed on 
boiling with NaClo. 


Nitric Acid, HNQ,. 


1. To the solution, in a test-tube, add a saturated solution 
of ferrous sulphate, and then concentrated sulphuric acid (free 
from HNO,); a brown ring between the FeSO, and H,SO, 
indicates HNO,. 


Phosphorus, P. 


Orthophosphates.—1. Magnesia mixture precipitates whtte 
MgNH,PO,,. 

2. AgNO, precipitates Aight-yellow Ag,PO,, soluble in HNO, 
and NH,OH. 

3.(NH ),MoO,+ HNO, precipitates ye//ow ammonium phos- 
pho-molybdate; composition variable. The precipitate is sol- 
uble in NH,OH, in excess of phosphoric acid, and is prevented 
by organic substances, such as tartaric acid. 

Pyrophosphates.—1. MgSO, precipitates whzte Mg,P,O,, 
soluble in an excess of either solution. NH,OH fails to pre- 
cipitate it from these solutions. On boiling it separates again. 
By this reaction pyro can be detected in the presence of phos- 
phoric acid. 3 

2. (NH,),MoO, + HNO, does not give a precipitate until 
orthophosphate is formed. Most of the pyrophosphates of 
the heavy metals (Ag an exception) are soluble in alkali pyro- 
phosphates (distinction from orthophosphates). 

3. AgNO, precipitates whzte Ag,P,O,, soluble in HNO, 
and NH,OH. Addition of an alkali aids the precipitation. 

Metaphosphoric Acid.—1. Magnesia mixture gives no pre- 
cipitate. 


PRELIMINARY EXAMINATION, 45 


2. (NH,),MoO, + HNO, gives no precipitate. 

3. AgNO, precipitates whzte AgPO,, soluble in alkali meta- 
phosphate solutions (distinction from pyrophosphates). 

4. Albumen gives a precipitate (distinction from ortho and 
pyrophosphates). 

5. Fusion with Na,CO, converts meta and pyro into ortho- 
phosphates. 


Potassium, K. 


1. PtCl, with HCI precipitates ye/dow crystalline (KCl), PtCl,. 
Evaporate to dryness. The precipitate is not dissolved by 
alcohol. 

Confirm.—By blowpipe and spectroscope. 


Selenium, Se. 


1. H,S precipitates ye//ow sulphide of selenium, soluble in 
({NH,),S. Upon heating the precipitate turns reddish yellow. 

2. SnCl,-+ HCl produces a ved precipitate of Se, which 
turns gray at a high temperature. 

3. Metallic copper, when placed in a warm solution of 
selenious acid, containing HCl, becomes dlack,; if the fluid 
remains long in contact with the copper, it turns bright ved 
from separation of selenium. 


Confirm.—By blowpipe tests. 


Silicon, Si. 

Silicates are determined by the separation of SiO, Fuse 
with Na,CO,-+ NaNO,, dissolve in HCl, and evaporate to 
dryness. Upon evaporation gelatinous silica will separate out. 
Upon heating and dissolving with HCl insoluble SiO, remains 
behind. 

Conjfirm.—By blowpipe test. 


Silver, Ag. 
1. HCl precipitates wzte AgCl, insoluble in HNO,, soluble 
in NH,OH. 


- 


40 A MANUAL OF PRACTICAL ASSAYING. 


2. Cu precipitates metallic Ag. 

3. KI precipitates ye/low AgI, insoluble in NH,OH, soluble 
in excess of reagent. 

Confirm.—By blowpipe test. 


Sodium, Na. 


1. (NaCl),PtCl, crystallizes from its concentrated solutions 
in ved prisms. 

2. KSbO, (in neutral or alkaline solutions) precipitates 
white NaSbO,. The reagent should be dissolved as wanted, as 
it is unstable in solution. 

Confirm.—By blowpipe and spectroscope. 


Strontium, Sr. 


1. NaOH, NH,OH, Na,CO,, (NH,),CO,, and Na,H PO, form 
precipitates which closely resemble those produced by these 
reagents with Ba salts. 

Confirm.—By biowpipe tests. 


Sulphur, S. 


I. BaCl, gives a white precipitate, BaSO,, when added to 
sulphuric-acid solutions. Practically insoluble. 
2. On addition of HNO, to sulphides H,S is given off. 


Tellurium, Te. 


1. H,S precipitates drown TeS, from acid solutions. Sol- 
uble in (NH,),S. 

2. Boiled with concentrated H,SO, there results a purple. 
violet solution, which fades upon further heating or dilution. 

Confirm.—By blowpipe tests. 


Tin, Sn. 


Stannous Oxide (SnO).—1. H,S precipitates dark-brown SnS, 
soluble in HCl, in alkalies; moderately soluble in yellow 
(NH,),9. 


PRELIMINARY EXAMINATION. 47 


2. HgCl, precipitates whzte Hg,Cl,, with excess black Hg 
(distinction from stannic compounds). 

3. AuCl, with free HCl or HNO,, a purple precipitate. 

4. Zn precipitates spongy Sn. 

Stannic oxide (SnO,). 

1. H,S precipitates yellow SnS,, soluble in HCl, in alkalies 

and alkaline sulphides. 

2. HgCl, no precipitate. 

3. AuCl, no precipitate. 

4. Zn precipitates spongy Sn. 

Conjirm.—By blowpipe tests. 


Titanium, Ti. 


1. NH,OH gives a bulky whz¢e precipitate, Ti(OH),, insol- 
uble in excess. 

2. Sn or Zn boiled in acid solutions after some time give 
pale-violet or blue solutions, subsequently a blue precipitate, 
which gradually becomes white. 

Conjirm.—By blowpipe. 


Tungsten, W. 


I. SnCl, produces a yellow precipitate on acidifying with 
HCl, and applying heat the precipitate acquires a beautiful 
blue color. | 

2. Heated with HCl and Zn the solution becomes purple, 
and then reddish brown. 

3. K,FeC,N, + HCl gives a deep drownish-red color; after 
some time a precipitate of the same color is produced. 


Uranium, U. 


1. NH,OH, KOH, and NaOH produce a yellow precipitate 
of uranic hydroxide and alkali. 

2. K,FeC,N, produces a reddish-brown precipitate. 

Conjirm.—By blowpipe test. 


48 A MANUAL OF PRACTICAL ASSAYING. 


Vanadium, V. 


1. K,FeC,N, produces a green flocculent precipitate, insol- 
uble in acids. 

2. Dissolved in H,SO, and Zn added the solution becomes 
successively green, blue, bluish violet, and lavender. 

3. An acidified solution of vanadates upon being shaken 
with hydrogen dioxide acquires a ved tint; if ether is then 
added, and ‘the solution shaken, its retains its color, the ether 
remaining colorless. 


Zinc, Zn. 


I. Alkali hydroxides precipitate whzte Zn(OH), , soluble in 
excess of precipitant. 

2. H,S precipitates (from neutral or acetic acid solutions) 
white ZnS. 

3. K,FeC,N, precipitates whzte Zn,FeC,N,, insoluble in 
very dilute solutions of HCl. 

4. (NH,),S precipitates wzte ZnS, insoluble in KOH and 
rita Os 

Conjirm.—By blowpipe test. 


TT al Ree Ve. 
APPARATUS AND OPERATIONS. 


THE general apparatus used in the ordinary course of an 
analysis or assay is all that will be discussed here. The 
special pieces of apparatus, such as the apparatus used in the 
analysis of gases, will be discussed under the head of the 
different determinations. 

Crushing and Pulverizing.—A small hand-crusher, or a 
small power-crusher, where power can be obtained, will be 
found very convenient for crushing small samples of ore, slag, 
etc. If such a crusher is not at hand, the crushing can be 
done in an iron mortar; but in a laboratory where much work 
is done a small jaw-crusher will save a great deal of time and 
labor. 

A cast-iron bucking-plate and muller are indispensable for 
fine pulverization of ore samples. The ordinary plate is 
2 2 feet and 1 inch thick, cast with flanges about 1 inch high 
on the two sides. The surface should be planed perfectly 
smooth. The muller or grinder is of cast iron, about 6 inches 
long, 4 inches wide, 13 inches thick in the middle and 1 inch 
thick at the two ends, so that the surface is convex. The sur- 
face should be planed smooth and true at all points. 

The crushed ore is spread upon the plate, a few ounces at 
a time, the left hand being placed on the muller so as to throw 
the weight of the body on it, whilst the right hand grasps the 
handle. The muller is moved back and forth, depressing the 
handle as it is brought forward and raising it when pushing 
the muller back. 

A small agate mortar and pestle wili be found indispen- 

49 


50 A MANUAL OF PRACTICAL ASSA VYING, 


sable, where wet determinations are to be made, fer finely pul. 
verizing ores, etc., which are decomposed with difficulty. As: 
the pulverizing in the mortar is a tedious operation, a quantity 
of the substance only slightly in excess of the amount required 
for analysis should be taken. Of course this small sample 
should be carefully taken from the general pulverized sample, 
so that it accurately represents the whole. 

Screening.—After the sample is cut down and pulverized 


on the bucking-plate it should be passed through a screen or 


sieve. What refuses to pass through the sieve is again bucked 


and screened until all has passed through. The usual sieve is. 
one of 80 or 100 meshes, This is sufficiently fine for samples. 
which are to be assayed by fire-assay, but samples which are 


to be treated in the wet way will frequently have to be still 
further pulverized in the agate mortar. The sieves come in 


nests comprising 20, 40, 60, 80, and 100 meshes, each nest being 
provided with a tin box and cover. Such a nest of sieves will - 


be found very convenient and useful in a laboratory doing 
metallurgical work. 
Storing Samples.—Small paper sacks, or, preferably, en- 


velopes made of heavy brown paper and provided with patent: 


end-fasteners, are very convenient for keeping the pulverized 
samples. Small wide-necked sample-bottles holding about 
four ounces each are sometimes used for this purpose. All 
samples should be properly labelled and filed away for a 
reasonable length of time. 

Moulds.—Cast-iron ingot moulds for casting bars of base 
bullion or silver bullion will be necessary where assays of 
bullion or alloys are to be made. 

Cupel-moulds and pestles are required for making cupels. 
They are made of both brass and steel, the brass moulds 
being preferable. They come in different sizes, those most 
used being moulds which will make cupels weighing about & 
srammes and 18 grammes, respectively. 

Moulds for pouring scorification and crucible charges are 
necessary. These should be of cast-iron, the depression being 
conical in shape, with the apex of the cone slightly rounded 


APPARATUS AND OPERATIONS. 5I 


off. They should be of two sizes, the smaller for scorification 
and the larger for crucible assays. 

Rolls.—A set of small steel hand-rolls for flattening out 
samples of gold and silver bullion, and gold cornets in the 
gold-bullion assay, will be found convenient. 

Weighing.—For a laboratory doing general work (both 
wet and dry assays) five balances will be found useful. Each 
of these balances should be provided with the proper set of 
weights. It is best to have separate weights for each balance. 

A. A rough scales for weighing large samples of ore, metals, 
etc. An ordinary grocers’ scales answers very well for this 
purpose. This balance should be provided with avoirdupois 
weights. 

B. A pulp-balance for weighing out ore for fire-assay. 
This balance should take 120 grammes in each pan, and should 
be sensitive to within 5 milligrammes. It should be provided 
with a set of gramme weights from 5 mgs. to 20 gms. It 
should also be provided with a set of assay-ton weights from 
mos A. ©. to 4 A. T. 

The system of assay-ton weights was devised by Prof. 
C. F. Chandler, of Columbia College. These weights are not 
only very convenient, but their use results in the saving of 
considerable time in the calculation of the results of gold and 
silver assays. As ores of the precious metals, as well as those ~ 
of the base metals, are weighed in pounds avoirdupois, whilst 
gold and silver are weighed in ounces Troy, the basis of the 
system is the number of Troy ounces in one ton avoirdupois 
(2000 pounds), which is 29,166.66 ounces. The assay-ton con. 
tains 29,166.66 milligrammes; hence if one assay-ton of ore is 
taken for assay and a silver button weighing 100 milligrammes 
is obtained, the ore will assay 100 ounces of silver per ton, as 
each milligramme in I assay-ton is equivalent to 1 ounce Troy 
per ton avoirdupois. If $ assay-ton were taken for assay, it 
would be necessary to multiply the result (in milligrammes) by 
2 to obtain the assay value, etc. 

C. An analytical balance for weighing out ore, etc., for 
analysis and weighing the results of wet determinations. This 


52 A MANUAL OF PRACTICAL ASSAYING. 


balance is also used for weighing out ore for scorification-assay 
in the case of rich ores and the buttons obtained by fire-assay 
for base metals. The balance should take at least 30 grammes 
in each pan, and should be sensitive to within 0.5 milligramme. 
It should be enclosed in a glass case, and should be kept free 
from moisture, fumes, etc. It should be provided with a set 
of gramme weights from 1.0 mgm. to 30 gms., and also with 
a beam-rider for weighing milligrammes and fractions of milli- 
grammes. The best balances are provided with agate knife- 
edges. 

D. A button-balance, for weighing the gold and silver 
beads and for weighing out samples of gold and silver bullion 
for assay. This balance should take at least I gm. in each pan, 
and should be sensitive to within |; mgm. It should be pro- 
vided with a set of gramme weights from I mgm. to I gm., and 
a beam-rider for weighing fractions of a milligramme. It should 
be provided with a glass case and agate knife-edges, and should 
»e kept free from dust, fumes, etc. The balance should not 
be exposed to the direct rays of the sun, as they cause expan- 
sion of the metal-work and throw it out of balance. 

E. A gold button-balance, for weighing the gold beads 
from the assay of gold ores. This balance should take at 
least 0.5 gm. in each pan, and should be sensitive to within 
;i, mgm. It should be provided with a set of weights from 
I mgm. too.5 gm., and a beam-rider for weighing fractions of 
a milligramme. It should be kept in a glass case, free from 
dust, etc., and should be provided with agate knife-edges. 

The last three balances should be set up on a perfectly 
firm support, and should be cleaned and adjusted from time to 
time. 

The balance should always be tested before weighing, to 
see if it is in perfect adjustment. 

The analytical balance should be provided with two watch- 
glasses, one for each pan. These watch-glasses are made with 
a glass lip or handle for convenience in removing. If they are 
not of equal weight, one can be filed on the bottom until they 


APPARATUS AND OPERATIONS, 53 


counterbalance, or the balance can be brought into adjustment 
by means of a small piece of platinum foil or wire. 

Accurate weighing is absolutely essential to accurate work. 
The most expeditious way of ascertaining the exact weight of 
a substance is to avoid trying the weights at random, but to 
proceed in a methodical manner. Suppose, for example, we 
wish to ascertain the weight of a precipitate whose weight 
subsequently turns out to be 0.535 gm. The precipitate is 
transferred to the left-hand pan of the analytical balance, and 
a 1-gm. weight is placed in the right-hand pan. The weight is 
found to be too much; so it is replaced by a 0.5-gm. weight, 
which is found to be too little. A o.I-gm. weight is now 
added, and is found to be too much; so it is replaced by a 
0.05-gm. weight, which is found to be still too much. The 
0.05-gm. weight is replaced by the 0.02 and the two o.oI-gm. 
weights, which is found to be still too much. One of the o.01- 
em. weights is removed, when the weight is found to be too 
little; hence the 0.005-gm. weight is added. The balance is 
found to exactly balance; hence this is the correct weight. It 
is best, in order to have a check on the weight, to add up the 
different weights on the pan and set down the total. As the 
weights are removed from the pan each weight is set down, 
and the sum taken after all are removed. 

The balance should be arrested each time a change is con- 
templated, such as removing weights, substituting one weight 
for another, etc. 

Substances liable to attract moisture from the air should 
always be weighed in closed vessels—as between two watch- 
glasses, in covered crucibles, or in a closed glass tube. The 
same applies to substances liable to lose moisture upon expos- 
ure to the air. 

Fluids should be weighed in small bottles provided with 
glass stoppers, or occasionally in accurately counterpoised 
beakers. 

A vessel should never be weighed whilst warm, as in that 
case its weight will invariably be too low. This is due to two. 
circumstances: highly heated bodies are constantly communi-- 


‘ 


54 A MANUAL OF PRACTICAL ASSAYING, 


cating heat to the surrounding air; the heated air expands 
and ascends, and the denser and cooler air flowing toward the 
space which the heated air leaves produces a current, which 
tends to raise the scale-pan. Every body condenses on its 
surface a certain amount of air and moisture, which amount 
depends upon the temperature and the hygroscopic state of 
the air and the temperature of the body. 

In weighing out a substance for assay or analysis it is 
generally best to take a certain definite quantity, aso.5 A. T., 
o.1 A. T., 1.0 gm., 0.5 gm., for example, rather than to weigh 
out an indefinite quantity, as 0.946 gm. Whilst this takes 
longer in the weighing out, the extra time expended in weigh- 
ing is more than made up by the time saved in the subsequent 
calculations. Moreover, when a definite even quantity is taken, 
errors in the subsequent calculations are much less liable to 
occur. 

Furnaces.—For fusions in fire-assaying either the wind- or 
muffle-furnace may be used. As the muffle-furnace is cleaner, 
and allows of a more perfect control of the heat, it is preferable 
to the wind-furnace. Where samples of bullion, etc., are 
to be melted, it will be necessary to have a wind-furnace; 
otherwise not. 

Both wind- and muffle-furnaces are built to use either solid 
or gaseous fuel. The gas-furnaces have several advantages, 
inasmuch as they allow of a more perfect control of the 
temperature, are cleaner, are readily started, and only con- 
sume fuel when the work is going on. On account of the 
facility with which the temperature can be controlled the 
U.S. Government have adopted gas-furnaces in many of the 
Government mints and assay-offices. Gas-furnaces can only 
be used where power is handy, as they require a pressure- 
blower to furnish the necessary blast. They are no more 
economical in fuel] than furnaces using coal or coke, but are to 
be recommended where power and gas are at hand, for the 
above reasons. Many excellent forms are kept in stock by 
the dealers. | 

’Where solid fuel is used coke or charcoal is the usual fuel 


APPARATUS AND OPERATIONS. 55 


in the wind-furnace, and coke or bituminous fuel in the muffle. 
furnace, although charcoal is also used in the muffle-furnace. 
The ordinary type of wind-furnace built for coke or char- 
coal is shown in Fig. 8. This furnace is built of red brick, and 
lined with one course of fire-brick. It should be firmly bound 
with angle-iron, and tied with tie-rods. The top of the furnace 









































WIND OR CRUCIBLE FURNACE 
Scale4in=1 ft, 


Fre. 8. 


is covered with a cast-iron plate, the cover or lid also being of 
east iron. The dimensions of the furnace shown in the sketch 


can be increased to any desired extent, but the same relative 


dimensions between the parts should be maintained when 
increasing the size. Where large amounts of silver bullion are 
to be melted the furnace will necessarily have to be considers 


56 A MANUAL OF PRACTICAL ASSAYING. 


ably larger than shown in the sketch. Where bullion is to 
be melted it is also well to provide the furnace with a chain- 
tackle for lifting the crucibles out of the furnace. Where 
retort silver from a pan-amalgamation mill is to be melted, 
the furnace should be provided with a sheet-iron hood, con- 
nected with the stack, for carrying off the fumes. 

There are many different styles of muffle-furnace in use. 
The furnace shown in Figs. 9 and 10 is designed to burn 





MUFFLE FURNACE FOR BITUMINOUS COAL. 
Scale % in= ray 


FIG. 9. Fic. I0. 


bituminous coal. Where good bituminous coal can be ob- 
tained, this is as satisfactory a furnace as can be built. The 
furnace is built of red brick, and lined throughout with one 
course of fire-brick. It should be firmly bound with angle-. 
iron, tied with iron tie-rods. Where good bituminous coal 
can be obtained, this furnace is preferable to a coke-furnace 
for the following reasons: It is quickly started, the tempera- 
ture is readily controlled, the consumption of muffles is much 
less than in a coke-furnace, the consumption of fuel is less (in — 


APPARATUS AND OPERATIONS. 57 


cost) at the ordinary prices of coal and coke, and the furnace 
has a longer life. 
Figs. 11 and 12 show a furnace constructed to burn coke. 





MU.FFLE FURNACE FOR COKE OR CHARCOAL, 
Scale 4 in=1 ft. 


Fic. 41, Fic. 12: 


This furnace is lined throughout with fire-brick, and bound 
with angle-iron and tie-rods. 

Heating Apparatus.—The fusion of substances with car- 
bonate of soda or mixed carbonates can be performed in the 
muffle-furnace or over a blast-lamp. Fletcher’s gas blast-lamp 
will be found almost indispensable in a laboratory provided 
with gas, for both fusions and the ignition of precipitates. 
Where gas is not at hand, Fletcher’s petroleum blast-lamp or 
an alcohol blast-lamp may be used for fusions, etc. However, 
if gas is not at hand, the muffle-furnace best answers the pur- 
pose, and in a metallurgical laboratory where a great number 
of determinations are made daily the muffle is preferable, as 
it allows of a number of fusions or ignitions to be made at 
one time. 

For fusions which do not require a very high temperature, 
as the fusion with caustic potash or the fusion with potassium 
bisulphate, the Bunsen burner or a good alcohol lamp is all 
that is required. : 


58 | A MANUAL OF PRACTICAL ASSAYING. 


For heating solutions, evaporations, etc., the gas-stove 
(Fletcher's) is an excellent piece of apparatus. When gas is 
not at hand a petroleum-stove can be substituted. Where a 
high temperature is not detrimental the top of the stove can 


be covered with a piece of wire-gauze. Where a high heat is — 


not wanted the wire-gauze can be covered with a piece of 
asbestos paper or asbestos cardboard. 

A most excellent piece of apparatus for evaporations, etc., 
consists of a sheet-iron plate, supported on four legs. This 
plate can be heated by gas- or petroleum-stoves or Bunsen 
burners. The temperature can be controlled by placing under 
the vessels containing the solutions pieces of asbestos paper of 
different thicknesses. 

Large vessels which are liable to be broken by the ebullition 
during heating are best supported on a sand-bath. A conven- 
ient form of sand-bath is an ordinary tin pie-plate partially 
filled with fine, clean sand. 

A water-bath will be essential for evaporations, which 
should not be heated above the boiling temperature of water. 
A good form of water-bath is a water-tight box of sheet copper 
18 inches long, 12 inches wide, and 4 inches deep. The top 
should have several round holes of different diameters, so that 
vessels of different sizes may be used on the bath. The open- 
ings should be provided with covers, so that they may be 
closed when not in use. The water-bath is partially filled with 
water, and the heat turned on. As soon as the water reaches 
the boiling-point it is ready for use. 

Where solutions require to be heated at a definite ested 


temperature, either higher or lower than that of boiling water, - 


a solution of calcium chloride, salt, etc., can be substituted for 
the water in the bath, or the solution may be evaporated ina 
hot-air bath which is kept at a fixed temperature. 

A hot-air bath will be found convenient for drying precipi- 
tates, evaporation of solutions, and determinations of moisture 
in certain substances. It should be provided with a thermom- 
eter, so that the temperature may be controlled. 

In a laboratory where gas is not at hand a very good 


APPARATUS AND OPERATIONS. 59 


apparatus for evaporations, etc., is an ordinary cook-stove. 
The evaporations can be performed on the top of the stove, 
the temperature being controlled by means of pieces of asbes- 
tos paper. In case quite high temperatures are necessary, 
the lids of the stove can be removed and asbestos cardboard 
substituted for them. The oven can be used for the drying of 
precipitates, samples, etc. The stove should be provided with 
a hood connected with a good draught to carry off the fumes. 
This hood can be conveniently made of wood lined on the 
inside with asbestos paper. The conduit of the hood may be 
connected with the same flue as the stove, thus insuring a 
good draught. 

Crucibles.—In an assay-office doing general work several 
different kinds of crucibles will be necessary. 

A. Graphite Crucibles.—These are used for the melting of 


samples of base bullion, silver bullion, gold bullion, etc. The 


best crucibles are made by the Dixon Crucible Co., and come 
in different sizes, holding from 4 ounces up to 5000 ounces. 
The melting is performed in the wind-furnace as follows: A 
good fire is started in the furnace, and when burning well the 
crucible and its contents are introduced, the spaces around the 
outside of the crucible being filled in with fresh coke or char- 
coal. The cover is then put on the furnace, and the damper 
opened. After each melt the crucible should be thoroughly 
cleaned whilst hot by means of ascraper. With proper care 
a crucible will serve for a large number of melts. . 
B. Clay and Sand Crucibles—These are used for the fusion 
in the crucible assay of gold and silver ores, and also for the 


~ fusion- or fire-essay of ores of the base metals. They come in 


a great variety of shapes and sizes, those most used being 
rated as 5, 10, 20, and 30 grammes (capable of holding charges 
for the assay of 5, 10, 20, and 30 grammes of ore). The best 
makes are the Colorado clay (made by the Denver Fire-clay 
Co.), the French clay, the Battersea (English make), and the 
Hessian sand (German make). In the western portions of the 
United States the Colorado-clay crucible has generally replaced 


' 60 A MANUAL OF PRACTICAL ASSA YING. 


the other makes, owing to the less cost of these crucibles and 
their general excellence. 

C. Forcelain Crucibles.—These are used for the ignition of 
precipitates, fusions which cannot be made in platinum or 
silver crucibles, and for the parting and annealing of the gold 
beads obtained in the assay of gold and silver ores, etc. They 
come in a great variety of sizes, the best makes being royal 
Berlin china and royal Meissen porcelain. 

D. Platinum Crucibles—These are used for the fusion of 
ores, furnace products, etc., with carbonate of soda, etc. They 
come in a variety of sizes, and are sold by the gramme, the 
present price being about 65 cents per gramme. They weigh, 
with the cover, about as many grammes as they hold cubic 
centimetres. As they are expensive they should be handled 
carefully. They should never be squeezed in the fingers to 
remove the fused mass. The best way to remove a fusion is 
to remove the crucible from the heat and quickly pour its 
contents out on a piece of clean platinum (the cover of a large 
crucible answers very well), or just before the fused mass 
solidifies insert a stout piece of platinum wire in it. The end 
of the wire should be bent in the form of a hook. As soon as 
the mass is cool, introduce a little hot water, and warm gently; 
in a few minutes the mass may be lifted out by means of the 
wire. The crucibles may be cleaned by heating with a little 
nitric acid (free from chlorine) or by scouring with a little finely 
pulverized red iron oxide. 

E. Rose Crucibles.—These are used for the ignition of cer- 
tain precipitates, which require to be ignited in an atmosphere 
of hydrogen, sulphuretted hydrogen, etc. They are made of 
porcelain, with a perforated porcelain cover and tube. The 
tube is attached to the supply of hydrogen or other gas. A 
very good substitute for a Rose crucible is an ordinary porce- 
lain crucible, and a clay tobacco-pipe for the cover and tube. 

F. Szlver Crucibles-—These are used for fusions where 
caustic soda or caustic potash is the flux. The crucibles with 
‘a gold lining are preferable. An alcohol-lamp should be used 
to heat these crucibles. 


a ee ee Se 
* 


APPARATUS AND OPERATIONS. 61 


Scorifiers.—These are used in the scorification-assay of 
gold or silver ores. They come in the following sizes: 24, 24, 
3, and 4 inches diameter. The best makes are the Colorado 
(Denver Fire-clay Co.) and the Battersea. 

Cupels.—The cupels used for the cupellation of the lead 
buttons carrying the gold and silver are made of bone-ash, the 
bones of horses or sheep being considered the best. It is better 
to make the cupels than to buy them ready-made. The bone-ash 
is mixed with sufficient warm water to hold it together without 
being too moist. By adding a little wood-ash or pearl-ash 
(potassium carbonate) to the water used in moistening the 
bone-ash the cupels will be more firm. The cupels are pre- 
pared by filling the mould with the moistened bone-ash, and 
driving the pestle with two or three light blows of a wooden 
mallet. They should be dried carefully by standing them in a 
warm place or in a place exposed to the rays of the sun, and 
all moisture and organic matter should be expelled previous 
to using by heating them in the muffle. 

Casseroles.—Casseroles and evaporating dishes are used 
for the decomposition of ores, etc., with acids and other liquid 
reagents, and for the evaporation of solutions. They are of 
porcelain and platinum, the porcelain being most generally 
used. They come in a variety of sizes holding from $ ounce 
up to 4 gallon. A very convenient size is the 4-ounce casse- 
role, which is 2 inches in diameter. The best makes are royal 
Berlin china, royal Berlin porcelain, and German porcelain. 

Beakers.—Beakers serve for a variety of uses in the labo- 
ratory. Lipped beakers are always preferable. Bohemian- 
glass beakers are the best. They come in a number of sizes, 
ranging from $ ounce up to 200 ounces in capacity. 

Beaker covers of convex glass (watch-glasses) will be found 
indispensable. 

Funnels and Filtering.—The best funnels are made of the 
best Bohemian or the best German glass. They come ina 
variety of sizes, ranging in capacity from 1 ounce to I gallon. 
They are also made in a variety of different forms for special 
purposes. 


62 A MANUAL OF PRACTICAL ASSAYING. 


There are a number of different makes of filter-paper, of 
which Schleicher & Schuell’s and Munktell’s best Swedish are 
the best for quantitative work. 

The best form of glass rods for filtering are made by cutting 
glass tubing into suitable lengths, and sealing the ends by 
means of the blast-lamp. They are light, and there is less 
liability of fracturing the beakers than in the case of solid- 
glass rods. | 

In preparing a funnel for filtration the paper should always. 
fit tight to the sides, and should be moistened with water after 
placing it in the funnel. In pouring a stream from the beaker 
on to the filter the stream should always be poured against a 
glass rod. The under side of the lip of the beaker should 
always be dry. In filtering, the rods should not have rubbers. 
on the end, as they are liable to introduce organic matter into 
the solutions. Rubbers on the rods are used in cleaning the 
beakers, and sometimes in removing the last particles of a 
precipitate from the beaker or casserole. 

Always use as small a filter as will allow of the proper 
washing of its contents. In washing allow all the solution to 
run through the filter before adding any wash-water. Fill up 
the filter with the water, and allow that to run through before 
adding any more. By this means excessive quantities of wash- 
water may be avoided. In washing by decantation, which is. 
sometimes necessary, allow the precipitate to settle, decant as 
closely as possible, pouring the solution on the filter; add 
water, stir well, allow to settle, and decant again closely before 
adding more wash-water. 

A filter-pump will be found a great convenience in a 
laboratory where many bulky precipitates are to be washed. 
Richards’ filter-pump, for water-pressure, is the best where 
water-pressure can be obtained. Where water-pressure cannot 
be obtained Bunsen’s filter-pump is the best. 

After a precipitate is thoroughly washed the funnel should 
be removed with the filter from the filter rack, and the precipi- 
tate thoroughly dried with the filter before ignition. ‘Whena 


APPARATUS AND OPERATIONS. 63 


filter-pump is used the precipitate and filter can be partially 
dried rapidly by drawing air through by means of the pump. 

Flasks.—The best flasks are made of the best Bohemian 
glass. A number of flasks of different sizes and different kinds 
will be found useful. Flat-bottom flasks of 8, 16, and 24 ounce 
capacity, provided with double perforated rubber stoppers, are 
useful for making wash-bottles. Pear-shaped flasks of 4 and 6 
ounce capacity will be found useful for copper determinations 
wreeroredccomposine’ ores, étc. Filtering flasks of 1 and 2 
pints capacity, and of heavy glass, are useful, especially where 
the filter-pump is used. A set of volumetric flasks, accurately 
graduated, and provided with ground-glass stoppers, will be 
indispensable for volumetric analysis. The following makes 
meesuMenieitasct: 50 CC., 100 cc., 250 cc., 500 cc., and I000 cc. 
They should not only be accurately graduated, with two marks 
on the neck of each, one called the holding-mark (the capacity 
of the flask when filled to that mark), and the other called the 
delivery-mark (the number of cubic centimetres the flask will 
deliver when filled to that mark), but, which is most important, 
they should be graduated so that they will bear the same rela- 
tive ratio to each other; that is, the 100-cc. flask should hold just 
half as much as the 200-cc. flask, and the 1000-cc. flask should 
hold just four times as much as the 250-cc. flask when each is 
filled to the holding-mark. This is of the utmost importance 
in volumetric analysis where aliquot portions are frequently 
taken. 

If it is desired to standardize a flask with great accuracy it 
can be done by counterpoising the flask on the balance with 
any convenient weight, adding weights to.those on the balance 
to an amount corresponding to the desired capacity of the 
flask, adding the proper amount of water, and marking the 
neck of the flask with the aid of a diamond ora good steel 
file. If an accurately standardized flask or pipette is at hand, 
others of twice, thrice, etc., its capacity can readily be pre- 
pared. 

Pipettes and Burettes.—These are constantly used in 
volumetric jnalysis. They are best purchased already gradu. 


64 A MANUAL OF PRACTICAL ASSAYING. 


ated, but their capacity should always be tested, especially as 
against the other measuring apparatus on hand, and as against 
each other. 

To test the capacity of a pipette, fill it to the proper mark 
with distilled water of 16° C., run this water into a weighed 
flask or beaker, and weigh the amount delivered. This weight 
should nearly correspond in grammes to the capacity of the 
pipette in cubic centimetres. A slight difference should be 
allowed for the expansion of water between o° and 16° C. 
One cc. of distilled water at 16° C. weighs 0.9988 gramme. 
In like manner the accuracy of a burette may be verified by 
weighing the amount delivered, taking any even number of 
cubic centimetres. 

A pipette should always be filled by suction to a little 
above the mark; then, by closing the top with the finger, the 
liquid may be allowed to run slowly out until the lower part 
of the meniscus is at the line. It will then (if correct) deliver 
the number of cubic centimetres marked upon it. Pipettes 
may have both a holding- and delivery-mark, but if used for 
delivery only the holding-mark is unnecessary. 

There are many different forms of burettes made, but those 
of Mohr and Gay-Lussac are the most convenient, and gener. 
ally preferred. Mohr’s burette, provided with Geissler’s glass 
stop-cock or the Gay-Lussac burette, should always be used 
for solutions liable to decompose rubber. 

In a laboratory where the volumetric solutions are in 
constant use it isa good plan to have a separate burette for 
each standard solution, and attach it, by means of a siphon, 
of glass tubing, and a glass stop-cock, to the bottle holding the 
standard solution. By this means the burettes are readily 
filled, and do not have to be emptied and cleaned after each 
set of determinations. 

As the success of volumetric analysis depends largely upon 
accurate measuring, too much care cannot be given to accu- 
rately graduating and reading the flasks, pipettes, and burettes. 

Tools.—A number of small tools will be required as 
follows: A set of three hammers, for pounding lead buttons, 


APPARATUS AND OPERATIONS. 65 


flattening silver-gold buttons for parting, and cutting out 
samples of bullion, etc. ; 

Shovels and pokers, and scrapers for cleaning out the muffle ; 

Crucible tongs, scorifier tongs, and cupel tongs, for fire- 
work. Small crucible tongs, for crucibles used in wet assays ; 

Cold-chisels, for cutting out samples of bullion ; 

A small anvil or steel plate, for hammering lead buttons 
and separating the buttons from the slag; 

Spatulas, for sampling, weighing out, mixing charges, etc. ; 

A set of small steel dies, from o to g inclusive, for marking 
bars and samples of bullion ; 

A pair of cutting shears and nippers, for cutting samples of 
bullion, etc. ; 

A pair of scissors, for cutting filter-papers, and a set of filter 
patterns ; 

Files, for cutting glass rods and tubing, marking flasks, etc.; 

An assorted lot of rubber stoppers, both perforated and 
plain ; 

An assorted lot of glass tubing and glass rods; 

An assorted lot of rubber tubing ; 

Platinum-wire and platinum-foil. 

Whilst most of the apparatus used in the analytical work 
can be purchased of the dealers, a great deal of it can be made 
in the laboratory with a little patience and ingenuity. The 
student should accustom himself to make such odd pieces 
of apparatus as he requires, as the chemist frequently needs 
apparatus, and cannot wait until it can be obtained from some 
distant dealer. 

In purchasing apparatus and supplies always buy the best, 
as cheap apparatus is dear at any price. Do not be extrava- 
gant in your purchases, as it is not necessary to have an 
immense amount of costly apparatus on hand in order to do 
good work. 


CHAP TE Ra Va 


REAGENTS. 


THE reagents used in both wet and dry assaying may be 
divided into the following general classes : 

Fluxes.—This class includes a large number of bodies, but 
generally they are substances which render others to which they 
are added more fusible, either by acting as solvents or as de- 
composing agents. They are either acid, basic, or neutral in 
their action. 

The following are the principal fluxes used in wet assaying 
or chemical analysis : 

Carbonate of Soda (Na,CO,). This acts,as a decomposing 
agent, and is used for the decomposition by fusion, either 
alone or in conjunction with other reagents, of silicates, etc. 
It should be pure, and free from moisture. 

Carbonate of Potasstum (K,CO,). This acts the same as 
sodium carbonate, with which it is frequently mixed. A 
mixture of the two carbonates in the proportion of their 
molecular weights is a most excellent flux for the decomposi- 
tion of certain silicates, clays, etc., which are difficultly decom- 
posed by either carbonate when used alone. The potassium 
carbonate should be pure and free from moisture. 

Potassium Bisulphate (KHSO,). This acts both as a de- 
composing agent and as an acid flux. Silica is not rendered 
soluble by fusion with this reagent, whilst iron oxide, alumina, 


etc., are converted into a form which is soluble. 
66 


REAGENTS. 67 


Sodium Hydrate (NaOH). This acts both as a decom- 
posing agent and a basic flux. It is used principally for the 
decomposition of sulphides and sulphates in the determination 
of sulphur. It is occasionally used for the decomposition of 
certain silicates and oxides, and is particularly adapted to the 
decomposition of certain organic compounds, converting them 
into compounds which are soluble in water. 

Potassium Flydrate (KOH). This acts the same as sodium 
hydrate, and is used for the same purposes. 

Sodium Nitrate (NaNO,). This acts as a decomposing 
agent, and also as an oxidizer. It should be pure, and free 
from moisture. The corresponding potash salt (K NO,) is also 
used for the same purposes. 

Flydrofluoric Acid (HF). This is one of the most power- 
ful decomposing agents, and by its means many silicates are 
decomposed, the silica being volatilized. 

The following are the principal fluxes used in dry or fire- 
assaying : 

Sodium Bicarbonate (NaHCO,), or the corresponding potas- 
sium salt. These act as desulphurizing agents, as basic fluxes, 
and in some cases as oxidizing agents. They should be free 
from moisture and coarse particles. As they are readily 
fusible, they can retain in suspension a large proportion of 
pulverized infusible substances without losing their fluidity. 

Borax, crystallized (2NaBO,, B,O,, 10H,OQ). This acts as 
an acid flux, and is sometimes used as a cover in place of salt. 
As it contains a large amount of water, it is usually used ina 
vitrified condition. It loses its water readily upon fusion. To 
prepare the vitrified borax (borax-glass), fuse it in an iron- or 
chalk-lined clay crucible, pour the fused mass out on a clean 
surface, and pulverize when cold. 

Litharge (PbO). Acts as a basic flux, an oxidizing and 
desulphurizing agent, and supplies the necessary lead in the 
gold and silver crucible assay. It should be free from red 
oxide of lead. White lead is sometimes used in its place. As 
it always contains silver, its silver contents should be deter 
mined and deducted from the results of all silver assays. 


68 A MANUAL OF PRACTICAL ASSAYING, 


Stlica (SiO,). This acts as an acid flux. Sometimes pow- 
dered glass is substituted for silica. Lime-glass makes the 
best flux, and when used for lead assays should be free from 
lead. 

Lead Flux. This is a mixture of sodium bicarbonate (16 
parts), potassium carbonate (16 parts), flour (8 parts), and 
borax-glass (4 parts). This acts as a flux, reducing agent, and 
desulphurizing agent. It is especially useful in the lead assay, 
and frequently forms the basis of the charge in the crucible 
assay of gold and silver ores. 

Black Flux. This consists of one part nitre and three parts 
argol (deflagrated). It is not much used. 

Black Flux Substitute. This consists of a mixture of flour 
(3 parts) and sodium bicarbonate (10 parts). It is sometimes 
used in place of lead flux. 

Potassium Cyanide (KCN). Acts as a powerful reducing 
and desulphurizing flux. It is frequently used for the determi- 
nation of lead, tin, bismuth, and antimony by fire-assay. For 
this purpose it should be quite pure, and free from sulphides 
and sulphates. 

Argol (KHC,H,O,). Commercial bitartrate of potash. 
This acts as a powerful reducing agent, and also as a basie 
flux. Its reducing power should be determined by fusion with 
litharge and sodium bicarbonate. 

Charcoal (C). Acts asa reducing agent and desulphurizer. 
Its reducing power should be determined. 

Salt (NaCl). Is used principaliy as a cover in crucible 
essays. 

Nitre (KNO,). This acts as a basic flux and powerful oxid- 
izing agent. Its oxidizing power should be determined. To 
determine its oxidizing power, make up the following charge, 
place it in a clay crucible, and fuse in a kot fire. Remove, 
pour cool, and weigh the lead button. The difference be- 
tween the weight of the button obtained and that given in the 
_ determination of the reducing power of the charcoal, divided 
by 1.5, gives the oxidizing power of the nitre per gramme. 


Cee |. 


REAGENTS. 69 


Ohare —-Lithatce., ... see es sO ems, 
EP eamoIGATDa cc's ele ele’ ve: Bl is 
MCE oe Lin's ofe'e'e << eet. 
EMAL E Mrs is'stetets) 6 els 14% ieee 


Metallic Iron (Fe). Acts as a basic flux and desulphurizing 
agent. Nails or iron wire about ¢ inch in diameter are the 
most convenient form. 

Metallic Lead (Pb). This acts as a basic flux and as a solv- 
ent or collector of the precious metals in the assay of gold and 
silver ores. It is used in the form of granulated lead in the 
scorification assay and in the form of sheet lead in the bullion 
assay. As it is never free from silver, its silver contents should 
be determined and the proper deduction made from the results 
of all silver assays. 

All of the above fluxes should be dry and pulverized. 

Solvents.—Whilst many of the fluxes described above act 
as solvents during fusion, only such solutions as act as sol- 
vents in wet analysis will be discussed. | 

Water (H,O). Water used in quantitative analysis for so- 
lution, dilution, etc., should always be distilled. 

Hydrochloric Acid (HCl). This acts as a powerful solvent 
either alone or in conjunction with other acids. Aqua regia 
(2HCl + HNO,) is one of the most powerful solvents, and the 
only acid in which gold and platinum are soluble to any great 
extent. It should be pure, and kept on hand of two strengths, 
concentrated and dilute. The specific gravity of dilute hydro- 
chloric acid should be 1.2. 

Nitric Acid (HNO,). Is a powerful solvent and oxidizing 
agent. It should be pure, and kept on hand in concentrated 
and dilute state. Fuming nitric acid is a most powerful oxid- 
izing and desulphurizing agent. The specific gravity of the 
dilute nitric acid should be 1.2. 

Sulphuric Acid (H,SO,). Is a powerful solvent, and is 
extensively used both as a solvent and a precipitant. The 
specific gravity of the concentrated acid is 1.84. The dilute 


7O A MANUAL OF PRACTICAL ASSAYING. 


acid is prepared by adding one volume of the concentrated 
acid to five volumes of water. 

Acette (HC,H,O,), Oxalte (H,C,O,), Crtric (HG 
and Tartaric Actds (H,C,H,O,) are weak solvents, and are much 
used for special purposes. Acetic acid comes in solution 
either as commercial, c. p. ordinary, c. p. glacial (99 p. c.), or 
c. p. anhydrous. The other acids come in the crystalline 
form, either commercial or c. p. In making up solutions of 
these acids it is best to use an excess of the reagent and make 
a saturated solution. 

Ammonium Acetate (NH,C,H,O,). Is a powerful solvent of 
lead salts, especially lead sulphate. The reagent is best made 
by adding strong acetic acid to strong ammonia-water until 
the solution is just acid. The corresponding salts of am- 
monia with citric or tartaric acids answer the same purpose, 
but are more expensive and no better than the acetate. 

Ammonia (NH,OH). Acts as a powerful solvent of chlo. 
ride and bromide of silver. 

Sodium Hyposulphite (Na,H,S,O,). Is a solvent of silver 
chloride, and is used largely in the lixiviation of silver ores. 

Potassium Cyanide (KCN). Isa solvent of gold and silver, 
and is extensively used in the leaching of gold ores. 

Ammonium Sulphide |(NH,),5]. Is a powerful solvent of 
the sulphides of arsenic, antimony, and tin. 

Precipitants.—There are a great number of precipitants 
used in wet analysis. Only a few of the more important will 
be discussed. 

Barium Chloride (BaCl,). Is used principally <3 a precipi- 
tant for sulphuric acid. In making up the solution one gm. of 
the crystalline salt is added to 10 cc. of water. One cc. of this 
solution will precipitate 0.0327 gm. SQ,. 

Hydrodisodic Phosphate (Na,HPO,). Is used principally as 
a precipitant for magnesia. In making up the solution I gm. 
of the crystalline salt is added to Io cc. of water. One cc. of 
this solution will precipitate 0.0112 gm. of MgQ. 


*, 
{= 


=. — 


REAGENTS. va 


Ammonium Oxalate [(NH,),C,O,,H,O]. Is used princi- 
pally as a precipitant forcalcium. In making up the solution 
1 gm. of the salt is added to 10 cc. of water. One cc. of this 
solution will precipitate 0.0394 gm. CaO. 

Magnesta Mixture. Isusedas a precipitant for phosphorus 
and arsenic. In making up the solution 1 gm. of MgSO, (salt), 
1 gm.of NH,Cl (salt), and 4 cc. of ammonia are added to 8 cc. 
of water. Onecc. of this solution will precipitate 0.024 gm. 
Oia. O).. 

Molybdate Solution. Is used asa precipitant for phosphorus 
and arsenic. In making up the solution 1 gm. MoO, is dis- 
solved in 4 cc. of ammonia and the solution is poured into 15 
cc. of HNO, (sp. gr. 1.2). One cc. of this solution will precip- 
itate 0.0013 gm. of P,Q,. 

Silver Nitrate (AgNO,). Is used principally as a precipitant 
for chlorine. In making up the solution I gm. of salt is added 
to 20 cc. of water. One cc. of this solution will precipitate 
0.0104 gm. of Cl. 

Potassium Permanganate (K,Mn,O,). Is used as a precipi- 
tant of MnO, in the volumetric estimation of manganese. The 
solution is made up in the manner described in Part II, Chap- 
ter XVI. 

Ammonia (NH,OH). Is used as a precipitant of iron, alu- 
mina, etc., and is an indispensable reagent in the laboratory. 

The strongest concentrated ammonia has a sp. gr. of 0.88. 
This diluted with two volumes of water has a sp. gr. of 0.96, 
which is the reagent commonly used. 

Ammonium Carbonate |(NH,),CO,]|. Is used as a precipi- 
tant of Zn, Mn, Fe, Ca, Ba,etc. Is an invaluable reagent. In 
making up the solution 1 gm. of the salt and 1 cc. of ammonia 
are added to 4 cc. of water. 

Ammonium Sulphide {(NH,),S]. Is used as a precipitant 
of Fe, Zn, Mn, Ni,and Co. To prepare the solution pass a rapid 
current of pure sulphuretted hydrogen through a solution of 
ammonia in the reagent bottle. Should be kept corked, and in 
a dark, cool place. As it loses its strength rapidly, it is best 
to prepare freshly from time to time. 


72 A MANUAL OF PRACTICAL ASSA YING. 


Ammonium Chloride(NH,Cl). Is used in conjunction with 
ammonia as a precipitant of iron, etc. It is best to prepare a 
saturated solution. 

Sodium Carbonate (Na,Co,). Is used as a precipitant of Zn, 
Fe, Mn, Ca, Ba, etc. A saturated solution is usually used. 

Sodium Sulphide (Na,S). Is used principally as a precipi- 
tant of the heavier metals and as a solvent for sulphides of ar- 
senic, antimony, and tin. To prepare the solution add I gm. 
of salt to 10 cc. of water. 

Sodium and Potassium Hydrates (NaOH and KOH). Are 
used as precipitants of Cu, Fe,AlO,, etc. To prepareeiire 
solution dissolve 1 gm. of the salt in 1o cc. of water. 

Sodium Acetate (NaC,H,O,). Is used as a precipitant of 
iron and alumina in the basic-acetate separation of these 
metals. The salt is generally used. 

Sodium Chloride (NaCl) and Sodium Bromide (NaBr). Are 
used as precipitants of silver in the volumetric estimation of 
silver (Part III, Chap. II) and in the special method for copper 
mattes (Parti @hapwly)), 

Platinic Chloride (PtCl,). Is used as a precipitant of potas- 
sium. To prepare the solution dissolve 1 gm. of the metal in 
aqua regia, evaporate to dryness and dissolve in 1 cc. HCl and 
9 cc. of water. One gramme of this solution will precipitate 
0.048 gm. of K,O. 

Flyaric Sulphide (Sulphuretted hydrogen, H,S). Is used 
principally as a precipitant of the heavy metals. To prepare 
the gas add dilute sulphuric acid to pure iron sulphide. The 
gas should be washed by passing it through water before using. 
If pure iron sulphide is not at hand it can be prepared by fus- 
ing iron nails with sulphur in the proportion of about 1 part 
iron to 2 parts sulphur, by weight. A very convenient gen- 
erator is shown in Figure 13. 

Sulphuric Acid (H,SO,). As a precipitant, is used princi- 
pally to precipitate barium. One cc. of the dilute acid will 
precipitate 0.4291 gm. Ba. 

Metallic Zinc (Zn). It is used for the precipitation of Pb, 


Ls ee 


REAGENTS. 73 


Cu, As, Sb, Ag, and Au (from cyanide solutions). The zinc 
should be free from these metals, and free from iron when used 
for the reduction of iron solutions. It is used in the form of 
sticks, sheets, or as granulated, zinc. To granulate, melt some 
bar zinc in a clay crucible, skim off the surface, and pour into 
cold water from a considerable height. 

Metallic Copper (Cu). Is used as a precipitant of mercury. 
Comes in the form of thin foil and sheets. 

Metalic Aluminium (Al). Is used asa precipitant of Cu 
and Bi. Comes as foil. 

Metallic Lead (Pb). Is used as a precipitant for cop- 
per. Either sheet lead, or preferably granulated test-lead, is 
used. 

Pure materials aneeit always be used. In making up the 
solutions distilled water should be used. The salts obtained 
from the dealers and labelled ‘“ chemically pure” are seldom 
absolutely so, and often afford a sediment or precipitate when 
the solutions are allowed to stand. Hence it is best to prepare 
the solutions in bulk and filter them off after they have been 
allowed to stand for some time. Tests should always be made 
for such impurities as are liable to interfere, or cause errer in 
the analyses. If such impurities are found, the amount will | 
have to be determined and an allowance made for it in the 
work, either by carefully measuring the amount of reagent used 
and making the proper deduction from the result of the analy- 
sis, or by running a blank analysis. The latter course is gen- 
erally preferable where really accurate results are required. In 
running a blank analysis the same amounts and kinds of re- 
agents are added to the proper amount of water as are used in 
the regular analysis. The solution is boiled, filtered, etc., as in 
the regular analysis. The weight of the final precipitate ob- 
tained in the blank analysis should be deducted from the 
weight of the precipitate obtained in the regular analysis. 

Reducing Reagents.—To this class belong those bodies 
which have the power of removing oxygen from its com- 
pounds. They are the reverse of oxidizing reagents. 


74 4A MANUAL OF PRACTICAL ASSAYING. 


The principal reducing reagents used in fire-assaying are 
as follows: Charcoal, Argol, Flour, Starch, Sugar, Potassium 
Ferrocyanide, and Potassium Cyanide. They have been dis- 
cussed under the head of ‘“ Fluxes.” 

The following are the principal reducing reagents used in 
wet analysis: 

Hydrogen (H). This is the most powerful reducing agent. 
Is used in the form of a gas, which should be dry and free from 
impurities, such as arseniuretted hydrogen. It is best prepared 
by treating zinc, or iron filings, with dilute sulphuric acid. 
Sometimes dilute hydrochloric is substituted for the sulphuric 
acid. The gas is frequently generated in the solution to be 
reduced as in the case of the reduction of a solution of ferric 
sulphate to ferrous sulphate in the determination of iron. (See 
Part li Ghap. XV 1.) 

Sulphuretted Hydrogen(H,5). Isa powerful reducing agent. 
The gas is generated in the manner described under the head 
of ‘“ Precipitants.” 

Sodium Sulphite (Na,SO,). This is a good reducing agent. 
It is frequently used for the reduction of ferric solutions. It 
separates Arsenious Sulphide, which is soluble in it, from the 
sulphides of antimony and tin, which are insoluble in it. 

Stannous Chloride (SnCl,). This is frequently used for the 
reduction of iron solutions for the volumetric estimation of 
iron. (See Part II, Chap. XVI.) 

There are many organic compounds, as solutions of sugar, 
tartaric acid, etc., which serve as reducing agents. 

Oxidizing Reagents.— Under this heading are comprised 
all bodies which readily yield up their oxygen. | 

The principal oxidizing reagents used in fire-assaying are 
Nitre, Litharge, Sodium Bicarbonate, and Ferric Oxide. 

The principal oxidizing reagents used in wet analysis are 
the following: 

Oxygen (O). This is the most powerful oxidizing agent, 
and is generated or produced in various different ways. 

Chlorine (Cl). Is a powerful oxidizer, and is readily gener- 
ated by treating bleaching-powder with sulphuric acid. 








REAGENTS. US 


Bromine (Br). Is a powerful and very convenient oxidizing 
agent. It is purchased in the liquid form, and is generally 
used as bromine water (water saturated with bromine). 

Potassium Permanganate (K,Mn,O,). Is a powerful oxidiz- 
ing agent, which is largely used in volumetric analysis. The 
standard solutions are made up as described for the determina- 
tion of iron (Part II, Chap. XVI). 

Potasstum Bichromate (K,Cr,O,). Is a powerful oxidizing 
agent, which is largely used in volumetric analysis. The stand- 
ard solutions are made up as described for the determination 
of iron (Part II, Chap. XVI). 

Nitric Acid (HNO,). Is a very powerful and convenient 
oxidizing agent, and is largely used for the oxidation of 
precipitates. Fuming nitric acid is the most powerful. It 
should be kept in acool dark place and should be handled 
carefully. 

Potassium Chlorate (KCIO,). Is a powerful oxidizer, yield- 
ing its oxygen with facility. Is largely used as an oxidizer in | 
fusions and for solutions. 

Sodium Nitrate (NaNO,). Is largely used as an oxidizing 
agent in fusions. The corresponding potassium salt (KNO,) 
may be substituted for the sodium salt. 

Hydrogen Peroxide (H,O,). Is a very powerful oxidizing 
agent. The objection to the use of this reagent is the difficulty 
of obtaining it in the pure state and its liability to undergo 
decomposition, it soon losing its strength. 

Ammonium Nitrate (NH,NO,). The salt is readily decom- 
posed upon heating, and is a good oxidizing agent. 

Indicators.—There are a number of color indicators 
which are extremely useful in volumetric analysis. These are 
fully discussed in Chapter XIII, ACIDIMETRY AND ALKALI- 
METRY, 

To the above classes of reagents might be added those 
which act as sulphurizing and desulphurizing agents. These are 
mostly included in the above, the principal sulphurizing re- 
agents being sulphur and sulphuretted hydrogen, and the prin- 


76 A MANUAL OF PRACTICAL ASSA YING. 


cipal desulphurizing reagents used in the wet way being the 
oxidizing reagents. In the dry way the principal desul- 
phurizing reagents have been discussed under the head of 
FLUXES. 

For a complete discussion of reagents, their preparation, 
etc., see Fresenius’ “‘ Qualitative Analysis.” 


PART If. 


GIA Per Reel, 
SILICA (SiO). 


THE method to be pursued in the determination of silica 
will depend on the character of the substance on which the 
determination is made. The following methods are extensively 
used in many of our metallurgical works: 

Iron Ores.—Most oxidized iron ores are decomposed by 
heating in a beaker with concentrated hydrochloric acid. Evap- 
oration to dryness is not necessary, and is to be avoided except 
where the ore gives up gelatinous silicaon heating. When evap- 
oration to dryness is necessary, the evaporation should be finished 
at comparatively a low temperature, preferably on the water- 
bath, otherwise some of the iron is liable to be converted into an 
insoluble form. After evaporation to dryness the mass is taken 
up with a small amount of hydrochloric acid and boiled. It is 
then diluted with distilled water and filtered, transferring the 
silica to the filter-paper with the successive additions of wash- 
water. When the washings are free from chloride of iron, 
which can be determined either by the yellow color of the 
filtrate or by testing with a solution of ammonium sulphocy- 
anate, which should turn red if iron is present, a few drops of 
dilute hydrochloric acid are dropped around the edges of the 
filter-paper, and the paper and contents washed a few times 
with boiling distilled water. This addition of hydrochloric 
acid to the filter-paper and subsequent washings is a precaution 

77 


78 A MANUAL OF PRACTICAL ASSAYING, 


necessary to dissolve any trace of iron, calcium sulphate, etc., 
which may have remained on the filter with the silica. The 
filter and its contents are then removed from the funnel, the 
paper being folded so as to thoroughly envelop its contents. 
It is then placed in a small porcelain crucible and ignited in the 
muffle furnace or over the blast-lamp. Previous drying of the 
paper and its contents is unnecessary. One gramme of the ore 
is the amount usually taken. A very convenient vessel for the 
_ solution and evaporation of the ore is a porcelain casserole, of 
about 100 cubic centimetres capacity, provided with a handle. 
Some ore, such as chromic iron ore, and magnetites carrying 
considerable titanium, will not be thoroughly decomposed by 
simple treatment with acids. In such a case the best method 
of procedure is to tuse une insoluble residue, after previous 
ignition, with c. p. carbonate of soda* in a platinum crucible, 
one to two grammes of carbonate being generally sufficient 
where one gramme of ore has been taken, or the ore may be 
fused directly with sodium carbonate and the silica determined 
as usual where a fusion is made. 

The fusion can be made over a blast-lamp or in the muffle. 
It should be complete, which will be indicated by the mass 
being perfectly liquid and quiet. Ten to twenty minutes will 
generally be sufficient time to bring the fusion to completion. 
During the last few minutes the crucible and its contents 
should be raised to a high temperature. 

When the fusion is complete the crucible is removed from the 
source of heat, and its bottom is dipped in cold water in order 
to chill the mass quickly, The fused mass is removed from 
the crucible by boiling water added from a wash -bottle. 
Slightly bending the crucible a few times with the fingers will 
creatly facilitate the removal, and will not injure the crucible 
if proper care is exercised. The washings and mass are poured 
off into a casserole provided with a convex glass cover, and 
hydrochloric acid added in slight excess. The solution is then 
evaporated to dryness, the evaporation being completed at 


* Many chemists prefer a mixture of equal parts of sodium and potassium 
carbonate. 


SITTCAS 79 


temperature not much above that of boiling water, otherwise 
the mass is likely to spit, and consequently there will be a loss, 
The mass is then heated at a temperature of about 120° C. until 
all the free hydrochloric acid is driven off. It is then taken up 
with water and a few cubic centimetres of hydrochloric acid, 
boiled, filtered, washed, ignited, and weighed. 

Silver-Lead Ores.—One gramme of ore is usually taken. 
{f the ore is oxidized, this is dissolved in seven cubic centi- 
metres of hydrochloric acid and treated in the same manner as 


in the case of iron ores, the precaution being taken to remove 


the lead and silver in the manner described below. If the ore 
is a sulphide, it is best to dissolve in four cubic centimetres of 
strong hydrochloric acid, three cubic centimetres of strong 
nitric acid, and evaporate to dryness. 

It is then taken up with a few cubic centimetres of hydro- 
chloric acid, boiled, and diluted with distilled water. The 
solution is then filtered off on to a filter-paper by decantation, 
and after all the chloride of iron, etc., is removed, about six or 
seven cubic centimetres of a warm solution of ammonium 
acetate added to the casserole, and its contents stirred with a 
glass rod provided with a rubber on the end. The ammonium 
acetate dissolves the sulphate and chloride of lead present, and 
the stirring serves to break up any clots of these salts which 
might not otherwise go into solution. Two additions of am- 
monium acetate are generally sufficient to dissolve all of the 
lead, although a third washing may sometimes be necessary. 

The ammonium acetate is usually prepared as follows: 
Some ammonia is poured into a beaker, and then acetic acid is 
added until the solution has an acid reaction, which is deter- 
mined by a piece of litmus-paper. The solution prepared in 
this way is quite warm, owing to the heat generated by the 
combination of the acetic acid and ammonia, and is ready for 
immediate use. | 

After all the lead is removed the silver may be removed by 
treating with a few drops, or cubic centimetres if much silver 
is present, of ammonia. 

The insoluble residue remaining in the sbeaaik is now 


80 A MANUAL OF PRACTICAL ASSAYING. 


washed on the filter with warm water, the filter washed once 
more, and a few drops of dilute hydrochloric acid poured 
around its edges. The filter and its contents are now washed 
again with warm water, and are then ready for ignition and 
subsequent weighing. 

For technical work the insoluble residue will generally be 
sufficiently close to the true amount of silica present to be 
considered as such. When an ore contains silicate of alumina or 
other insoluble compounds, if an accurate determination is 
required it can be made by fusion with sodium carbonate, as 
in the case of iron ores. 

On many ores a direct fusion of the ore with acid sulphate 
of potassium (KHSQO,) yields very good results. To make 
this fusion one gramme of ore is mixed with five grammes of 
potassium bisulphate in a porcelain crucible. The ore and 
flux should not fill the crucible much more than one-third full. 
The contents are then heated over the flame of a Bunsen 
burner or spirit-lamp until the fusion becomes quiet. The 
heat should be low at first in order to prevent loss by rapid 
boiling, and should be gradually increased until it is at a dull 
red. The fusion will usually take about fifteen minutes. When 
it is completed the crucible is removed from the source of 
heat and allowed to cool.. When sufficiently cool the mass is 
removed from the crucible by boiling water and about thirty 
cubic centimetres of water added, and the whole brought toa 
boil in order to thoroughly disintegrate the mass. The solu- 
tion is then ready for filtration and subsequent ignition, which 
is performed as before, more careful or longer washing with 
ammonium acetate being required if lead is present, as the 
lead is all in the form of sulphate. 

Slags.—lIn the case of lead slags the method to be pursued 
will depend on the manner in which the sample was taken. If 
the sample was taken on a rod* and chilled suddenly the silica 
may be determined by treating half a gramme in a small casse- 
role of about 100 cubic centimetres caj‘acitv, witk about two 


(eee Ss ee ee 





* See Part I, page 18 





Sil ICA: SI 


\ 

cubic centimetres of water, and stirring with a glass rod, then 
adding two or three cubic centimetres of strong hydrochloric 
acid and stirring again. This addition of water and stirring 
prevents the slag coagulating and sticking tothe bottom of the 
casserole, which it would otherwise do, and consequently would 
be difficult to decompose. A few drops of strong nitric acid are 
now added, the casserole being covered with a convex glass to 
prevent loss by effervescence, and the contents stirred again. 
Sufficient nitric acid should be added to decompose whatever sul. 
phides are present and oxidize the iron, leaving a slight excess of 
nitric acid in solution. A considerable excess of acid is to be 
avoided, as this would only prolong the evaporation, and cause 
loss of time. The mass is then evaporated to dryness, care 
being taken not to raise to such a temperature as to cause 
the gelatinous silica to spit. The subsequent driving off of 
the free hydrochloric acid may be facilitated by breaking up 
the lumps with a glass rod, and also by moistening with a few 
drops of water once or twice, and heating to dryness again. 
It is essential that all of the free acid and water should be driven 
off, in order that all of the silica may be rendered insoluble. 
After the first evaporation to dryness the casserole can be re- 
moved to a warmer place, care being taken not to heat to such 
a degree that the iron will be rendered insoluble. If iron is to 
be determined in the filtrate from the silica, the mass should 
not be heated to a temperature much over 110° C., as chloride 
of iron is volatile at quite a low temperature. After the free 
hydrochloric acid is driven off the casserole is removed from 
the source of heat, and the mass moistened with a little water, 
and about two cubic centimetres of hydrochloric acid added. 
The contents of the casserole are then brought to a boil. 
After diluting with water the silica can be filtered off, dried, 
ignited, and weighed, as in the case of silver-lead ores. 

The silica should be white, and there should be no gritty 
particles in the bottom of the casserole after solution. In the 
analysis of something over a thousand different samples of lead 
blast-furnace slags the writer has never yet encountered a slag 
which did not yield to this method of treatment, except in the 


82 A MANUAL OF ‘PRACTICAL ASSAYING. 


case of slags containing barium. If the slags contain barium, 
some sulphate of barium, which is insoluble, will invariably be 
formed when the sulphides are oxidized with the nitric acid, 
and be precipitated with the silica. 

This method of decomposing lead slags has been tested by 
the writer and others, a number of times, by fusing the insol- 
uble residue, obtained as above, with carbonate of soda, and 
determining the silica in the regular manner, with results 
agreeing so closely with those obtained by weighing the in- 
soluble residue as to prove the accuracy of the method—at 
least for all technical purposes. 

A determination may be made in this way in less than forty 
minutes. In case the slag contains barium, a good method of 
procedure is to weigh the insoluble residue, and fuse it with 
about a gramme and a half of carbonate of soda in a platinum 
crucible. The fused mass is then removed from the crucible, 
and dissolved in water by boiling. It is then filtered through 
a small filter, and washed thoroughly with warm water to 
remove all the silicate and sulphate of sodium. This can be 
determined by acidifying the washings with a few drops of 
hydrochloric acid, heating, and adding a few drops of barium- 
chloride solution. The carbonate of barium is then dissolved 
on the filter-paper with dilute hydrochloric acid, and several 
subsequent washings with warm water into a clean beaker, 
and after bringing the solution to a boil the barium is precipi- 
tated by the addition of a few drops of sulphuric acid, and de- 
termined as barium sulphate, as described in Part II, Chapter 
XXV. 

The weight of the barium sulphate thus determined may 
be deducted from the weight of the insoluble residue, the dif- 
ference being considered as silica. This determination of the 
silica by difference is generally considered sufficiently accurate. 
If greater refinement is necessary, the silica may be determined 
directly in the filtrate by acidifying with hydrochloric acid, 
and evaporating to dryness, as in the case of an ordinary 
fusion for silica. This evaporation takes considerable time on 
account of the bulk of the liquid, and liability to loss through 


SILICA. 83 


spitting, unless the evaporation takes place slowly. (See 
determination of silica in slags, etc.) An excellent method 
fore technical purposes is described in Chapter XXV, page 
B28. 

The same method may be used for the determination of 
silica in ores containing barium sulphate. The chemist will 
sometimes be called upon to analyze slags where the sample 
has not been taken in the manner described, as, for example, a 
piece of lump slag broken from a cold pot or cone. In this 
case the slag will very rarely be decomposed by direct treat- 
ment with acids. <A direct fusion of the slag in platinum is not 
safe, as there is a liability of the lead, which the slag contains, 
attacking the crucible. This difficulty can generally be obvi- 
ated in the following manner: Mix one half a gramme of the 
slag with about one and a half grammes of sodium carbonate, 
and transfer toasmall platinum dish (of about 25 cc. capacity). 
Place in the muffle, and heat till the mass cinters together, 
care being exercised not to heat sufficiently long or to a suffi- 
ciently high temperature to fuse the mass, or else the lead is 
liable to be reduced and injure the platinum. As soon as the 
mass has cintered, remove from the muffle and cool. If the 
cintering has been properly performed the mass will almost 
invariably be decomposed by the addition of water and hydro- 
chioric and nitric acids, when the silica may be determined in 
the manner described above. A platinum crucible may be 
used in place of a dish, but a dish is preferable, inasmuch as if 
a crucible is used the mass is liable to fuse around the edges 
before it has begun to cinter. When barium is present fuse 
the insoluble residue as before. 

Iron Blast-furnace Slags.—The first method described 
above does very well for the determination of these slags for 
technical purposes, the sample when taken being suddenly 
chilled. According to some authors, the decomposition is not 
as good as in the case of lead-slags, but from all the results 
which the author has seen he would say that they were 
sufficiently close to check the workings of the furnace, for 
which the determinations are usually made. When the sample 


oa on 
> ’ « 


84 A MANUAL OF PRACTICAL ASSAYING. 


has not been suddenly chilled on taking, the best method is to 
fuse one half a gramme of finely pulverized slag with about 
three grammes of sodium carbonate. Remove fused mass 
from the crucible, and determine as in the case of fusion of 
iron ores. 

Copper-furnace Slags.—These may be treated in the 
same manner as lead slags. 

Fused Ore.—This may be sampled and treated in the 
same way as lead slags. Whether the chilled sample of ore 
will be decomposed in acids or not, depends upon its composi- 
tion and the completeness of the fusion before the ore was 
drawn from the furnace. Very frequently it will not decom- 
pose. Under these circumstances, the insoluble residue which 
is free from lead, must be fused with sodiiim carbonate and 
the silica determined as before. 

Mattes.— These will seldom decompose completely in 
acids, owing to the slag which is mixed with them mechani- 
cally. Generally the insoluble residue will have to be fused 
with sodium carbonate if an accurate silica determination is 
required. 

Limestones.—As the silica of most limestones is present 
in the form of slate or quartz, the insoluble residue will gener- 
ally represent the amount of silica present. The limestone 
should be dissolved in hydrochloric acid, using about 6 to 7 
cc. of acid for 1 gramme of limestone,—the amount generally 
taken,—and a few drops of nitric acid to decompose any pyrite 
that may be present. In the case of a limestone carrying clay, 
the insoluble residue will have to be fused with sodium carbon- 
ate, as above. 

Fire-clays, Marls, etc.—As these substances contain sili- 
cate of alumina, which is not decomposed by acids, 1 gramme 
of the substance is fused direct with about 5 or 6 grammes of 
carbonate of soda, and the silica determined as usual. When 
the alumina is also to be determined, the insoluble residue can 
first be determined by evaporation with acids, as in the case 
of iron ores. The silica is then determined. by fusion with 
sodium carbonate as before, the difference between the per- 


SILICA. 85 


centage of silica and the percentage of insoluble residue being 
the percentage of alumina (Al,O,). When barium is present, 
the method of procedure after fusion of the insoluble residue 
is the same as in the case of the determination of silica in lead 
slags containing barium. 

Note.—In nearly all cases where an ore or product does 
not contain lead and a fusion is necessary to decompose it, the 
fusion may be made directly, thus frequently saving time. 
Where an ore is known to contain silicate of alumina, and the 
alumina is to be determined, it is best to obtain the insoluble 
residue, weigh it, and then fuse, determining the silica as 
before and the alumina by difference, or directly in the filtrate, 
from the silica. 

Pig-iron, Steel, etc.—The following method, proposed by 
Dr. Drown,* for the determination of silicon in pig-iron, etc., 
is used in some of our largest metallurgical works, and is as 
accurate and rapid as any: 

Treat I gramme of finely pulverized iron or steel in a cov- 
ered casserole with 10 cc. of water and about 8 cc. of concen- 
trated nitric acid, until action ceases. Add 4 cc. of sulphuric 
acid and heat on an iron plate or sand-bath until the nitric 
acid is all expelled. This evaporation can be facilitated by 
conducting it ina platinum dish with a strong-flamed Bunsen 
burner below and another from a blast-lamp above, the latter 
flame being directed downward upon the surface of the solu- 
tion in the dish. 

When the evaporation is complete, which will be indicated 
by dense white fumes of sulphuric anhydride, the silica will 
all be insoluble. Remove from the source of heat and cool. 
When the contents of the dish are cold, add cold water, about 
AO cc., carefully, to prevent spitting, and a few cubic centi- 
metres of hydrochloric acid. Heat, filter, wash, ignite, and 
weigh as usual. The addition of considerable water and 
hydrochloric acid is necessary to dissolve the ferrous sulphate 
formed during evaporation. After the silica is transferred to 





* Transactions of the American Institute of Mining Engineers, Vol. VII, 
p- 346. 


86 A MANUAL OF PRACTICAL ASSAVING. 


the filter, it should be thoroughly washed with hot water and 
hydrochloric acid, as in iron ores. In the case of ferro-silicons 
where the percentage of silicon is high, this treatment with 
acids will fail, except by repeated additions of fresh acid and 
repeated evaporations. In this case a shorter method is to 
fuse I gramme of the pulverized metal with sodium carbonate 
in a covered platinum crucible. The silicon is converted into 
a sodium silicate and the spongy iron remains in a finely- 
divided condition, and is readily attacked by acids. After 
fusion is complete, remove from heat, cool, and dissolve in 
hot water and hydrochloric acid. Evaporate to dryness, and 
determine silica as in fusion of iron ores. 

The silicon is determined as silica and weighed as such. 
From the weight of the silica calculate the percentage of sili- 
con as follows: Multiply the weight of the silica found by 7 
and divide the result by 15; the quotient will be the weight 
of the silicon in the amount of substance taken. 

Note.—The purity of silica can always be tested in the 
following manner: Brush the insoluble residue into a weighed 
platinum crucible, moisten with pure concentrated sulphuric 
acid, and add one gramme of ammonium fluoride. Place the 
lid on the crucible and incline it in its support; then heat 
gently by a burner or spirit-lamp, allowing the flame to play 
around the top of the crucible. Continue this heating (it 
should always be performed under a hood with a good draught? 
until all the sulphuric acid is expelled. Then heat the crucible 
strongly, removing the cover towards the last of the operation. 
cool and weigh the crucible, and repeat the operation, if nec- 
essary, until the crucible ceases to lose weight. The loss in 
weight represents the silica expelled as silicon fluoride, and il 
the silica as previously determined was pure, should equal its 
weight. Whatever remains in the crucible, if anything, may 
be alumina, barium sulphate, ferric oxide, etc. If these con- 
stituents are to be determined, they may be obtained in 
solution, with the exception of barium, by fusing with acid 
potassium sulphate. | 

Titaniferous Ores.—Many iron ores, especially magnetites, 


SILICA: 87 


contain considerable quantities of titanium. None of the 
above methods will serve to thoroughly decompose such ores. 
The following method, proposed by Dr. Drown,* is in general 
use: Fuse I gramme of ore in a platinum crucible with sodium 
carbonate. Dissolve in warm water and hydrochloric acid, 
and after solution is effected add an excess of sulphuric acid 
(40 cc.) and evaporate until all the hydrochloric acid is driven 
off, thus rendering the silica insoluble. Dissolve the ferrous 
sulphate in water and hydrochloric acid, heat to effect solution, 
filter, wash with warm water and hydrochloric acid, ignite, and 
weigh the silica. 

Note—The best Swedish and German filter-papers, such 
as Schleicher & Schuell’s c. p. paper, leave such a small quan- 
tity of ash after ignition that the weight of the filter-ash may 
be disregarded when this paper is used. Should pure filter- 
paper not be at hand, the ash of the paper should be deter- 
mined as follows: Place about six pieces of the paper to be 
used in a glass funnel, and wash with warm water containing 
several cubic centimetres of hydrochloric acid. After washing, 
roll the paper together, place in a crucible, dry, ignite, and 
weigh. From the total weight calculate the weight of one 
piece of paper. The weight thus obtained should be deducted 
from the combined weights of the silica and filter-ash in each 
determination. 

Bauxite.—As this mineral frequently contains titaniun, a 
method for its separation must be adopted in determining the 
value of an ore and its silica contents. Fuse 0.5 gm. of the 
finely pulverized mineral with potassium bisulphate in a cov- 
ered platinum crucible. Dissolve the fused mass in hot water, 
filter, wash, dry, ignite, and weigh. Treat this residue with 
hydrofluoric acid, and should a residue remain after expelling 
the silica, weigh it and deduct this weight from the weight of 
the insoluble residue as obtained, the difference being the 
weight of the silica.t 





* Transactions of the American Institute of Mining Engineers, Vol. X, 


p- 143. 
+ Mineral Resources of the U. S. 1892. Washington, 1893. 


Ci alte heen 


SULPHUR (S). 


WHILST there are a great many methods in use for the de- 
termination of sulphur in ores, furnace products, etc., the author 
must confess, after having tried a great number of different 
methods, that he has not as yet found a method which is accu- 
rate and at the same time rapid. | 

Fahiberg-Iles’ Modified Method.—This method was first 
proposed by M. W. Iles* for the determination of sulphur in 
certain organic compounds which are extremely difficult to 
decompose by ordinary means, such as treatment with acids or 
an ordinary fusion. It consists in decomposing the substances 
by fusion with caustic alkali, subsequent solution of the fused 
mass in water, oxidation of the sulphur, and determination as 
barium sulphate. The method is largely used for the determi- 
nation of sulphur in ores and furnace products,} and is accurate 
if the precaution is taken to remove all of the silica which the 
solution may contain before addition of the barium solution. 
This is a precaution which is not mentioned by the author of 
this method or by any of the text-books, but is a precaution 
which the writer has found by numerous experiments to be 
essential, owing to the fact that if the silica is not removed a 
large portion of it will be precipitated together with the barium 
sulphate and be weighed as such. The method as modified by 
the writer is as follows: 

Fuse 1.0 gramme of substance with from one to two sticks 
of potassium hydrate (the c. p. caustic potash by alcohol should 


_——— 








* School of Mines Quarterly; American Chemical Journal; etc. 
+ School of Mines Quarterly. 
88 





| 





SULPHUR. 89 


be used, as any other generally contains sulphur. It should 
always be tested for sulphur, to be sure that it contains none) 
in a silver crucible (a crucible lined with gold is preferable, as 
the alkali generally attacks the silver of the crucible to a slight 
extent) over a spirit-lamp. The best method of making the 
fusion is to place the potassium hydrate in the crucible and 
heat over the spirit-lamp (gas cannot be used, as it always con- 
tains sulphur compounds) to quiet fusion. Then remove the 
lamp from underneath the crucible, brush the substance into it, 
and heat for from 5 to 30 minutes until the substance is 
thoroughly decomposed. Remove the crucible and allow it to 
cool; as soon as cold dissolve the mass out with warm water 
into a beaker, and when it is all transferred to the beaker bring 
its contents to a boil and filter through a ribber filter-paper. 
Wash with boiling water until the washings come through free 
from sulphides or sulphates. Add from 20 cc. to 4o cc. of 
bromine water to the filtrate and heat to about go degrees C., 
and then acidify with hydrochloric acid. If the substance con- 
tains silica, it will now be in solution, and must be removed by 
evaporating the solution to dryness, heating and dissolving 
with water and hydrochloric acid, and filtering off the silica thus 
rendered insoluble. (See Chapter I.) 

To the filtrate from the silica, after boiling, add a solution 
of boiling barium chloride until all of the sulphur is precipitated 
as barium sulphate. By heating the solution of barium chlo- 
ride, before adding it to the solution, the barium sulphate is 
precipitated almost immediately, which is not the case if a cold 
solution of barium salt is used. After the addition of the 
barium chloride the solution is brought to a boil and then re- 
moved to a warm place and allowed to settle. After settling, 
it is filtered, washed thoroughly with boiling water, and then 
with a few drops of dilute hydrochloric acid dropped around 
the edge of the paper and again twice with hot water. It 
should be washed until the washings no longer give a precipi- 
tate with silver-nitrate solution. 

The precipitate is now dried, together with the filter-paper, 
and when dry transferred to a crucible by inverting the filter. 


go A MANUAL OF PRACTICAL ASSAYING, 


paper in the crucible and gently rolling in the fingers. (See 
Chapter XXV, Barium.) The crucible should be placed on a 
large clean watch-glass so that any particles which may fly out- 
side of the crucible can be recovered. After all that is possi- 
ble is removed from the filter-paper, it is rolled up and 
placed on the lid of a platinum crucible and burned by 
holding the platinum over the flame of a burner or spirit-lamp. 
The ash of the filter-paper is then added to the contents of the 
crucible, and the whole ignited in the muffle or over the blast- 
lamp. The crucible is then cooled and its contents should be 
found perfectly white. The precipitate is now transferred from 
the crucible to the watch-glass of the balance and weighed. 
The weight of the barium sulphate, less the known weight of 
the filter-ash, multiplied by 0.13734, will be the weight of the 
sulphur present in the amount of substance taken. 

When silica is not present the evaporation to dryness of the 
filtrate from the solution of the fusion can be omitted, thus 
greatly shortening the method. This method is universal in its 
application, but unfortunately requires considerable time, ow- 
ing to the time required to evaporate the solution to dryness, 
and drive off the free hydrochloric acid for the precipitation of 
the silica, which must be conducted slowly on account of the 
large amount of salts present. When evaporation to dryness 
is not necessary, a determination may be made in less than an 
hour and a half. 

Second Method.—The following method is frequently used 
in lead- and copper-smelting works for the determination of 
sulphur, and whilst it is not as accurate as the method pre- 
viously described, it has the advantage of being rapid, and con- 
sequently would be used where time for an accurate determina- 
tion is not available : 

Treat one gramme of ore in a flask (about 200 cc. capacity) 
with three to four grammes of potassium chlorate and 7 cc. of 
nitric acid, the acid being added as follows: About 3 cc. at 
first, and then I cc. from time to time. When all the acid 
has been added, heat to boiling on a sand-bath and evaporate 
off the excess of acid. All but about 2 cc. of acid should be 


SULPHUR. gl! 


expelled. The potassium chlorate and nitric acid oxidize the 
sulphur in the ore, and in the case of a heavy sulphide more 
potassium chlorate may be necessary. The solution, after 
boiling, should show no undecomposed particles of sulphides 
and no globules of yellow sulphur, which will sometimes form 
if the oxidation has been imperfect. kemove from the source 
of heat, dilute with about 50 cc. of water, and add a saturated 
solution of sodium carbonate in excess. The sodium carbonate 
precipitates the lead, iron, etc., and the excess is added to 
decompose the sulphates of lead and calcium which may have 
formed during solution. Boil for from thirty minutes to one 
hour, adding water from time to time to keep the bulk of the 
solution about the same. Filter through a fluted filter into a 
beaker, and wash until the washings no longer show the pres- 
ence of sulphuric acid. Acidify the filtrate with hydrochloric 
acid, and boil to expel the carbonic acid. When the carbonic 
acid is all expelled the solution is ready for the precipitation 
of the sulphuric acid with barium-chloride solution, and the 


‘determination of the barium sulphate as before. If the ore 


contains barium sulphate it will remain undecomposed with the 
precipitate of mixed carbonates. 

Matte Fusion.—The writer has frequently had occasion to 
make use of this method to obtain data upon which to calcu- 
late a furnace charge when time was wanting in which to make 
an accurate sulphur determination. 

This assay is made in order to determine the amount of 
sulphur, or matte-forming material, which an ore contains. It 
is at best only an approximation, but generally gives a result 
which is a sufficiently close approximation to the actual amount 
of matte which an ore will produce in the blast-furnace to be 
of value for metallurgical purposes. It has the advantage of 
being a rapid method, which is frequently of the utmost impor- 
tance in a smelting-works. This method takes about 20 
minutes, whilst a sulphur determination in the wet way, even 
within reasonably close limits, cannot be made in much less 
than an hour and a quarter. 


92 A MANUAL OF PRACTICAL ASSAYING. 


A charge which will generally give very good results is as 
follows: 


Ore ete aye rele iene se epe ves.) 5° Claim 
ba fale brouog CCH heed ira Sega HAG > 
CSIYAT COR Lan wer mera eG rie oye 3 es 


One or two nails, points down. 


The charge is thoroughly mixed in an ordinary clay cruci- 
ble and placed in the furnace, the time of fusion with a hot fire 
being about 15 minutes. After the fusion is complete the 
crucible is removed from the furnace, the nails drawn out, and 
the assay poured. As soon as the cone is cool it is removed 
from the mould and the slag broken off from the matte button, 
which is then weighed and the percentage calculated. In the 
case of a lead ore a lead button will also be found below the 
matte, but this is easily separated from the matte button. The 
matte button may be generally considered as containing about 
30 per cent sulphur, although the amount of sulphur which it 
will contain will vary somewhat, according to the nature of the 
ore. Theoretically the button should contain 36.3 per cent 
sulphur, matte being considered as FeS. However, a pure 
matte is seldom produced, as the ores generally contain impuri- 
ties such as zinc, copper, lead, arsenic, antimony, etc. A num- 
ber of analyses of matte buttons produced in this way show 
that an average of 30 per cent sulphur is reasonably close. 

Volumetric Method.—The following volumetric method 
was suggested by Alexander’s method for the determination 
of lead (see Part II, Chapter VIII). The method requires a 
standard solution of ammonium molybdate, which is prepared 
by dissolving 30.7 gms. of ammonium molybdate in water and 
diluting to rooo cc. Each cc. of this solution should be equiv- 
alent to 0.005 gm. of sulphur. To standardize the solution 
weigh out two portions of from 0.3 to 0.5 gm. of pure sheet 
lead, dissolve in a few cc. of dilute nitric acid, add a slight 
excess of sulphuric acid, and boil to drive off the nitric acid. 
Cool, add a slight excess of ammonia, and then strong acetic 


SULPHUR. 93 


acid in excess. Heat to dissolve the lead sulphate and dilute 
with hot water to about 180 cc., when the solution is ready for 
titration with the molybdate solution. The molybdate solu- 
tion is run in from a burette with constant stirring, and a drop 
of the solution tested from time to time on a porcelain plate 
with a drop of a solution of tannin. As soon as the molybdate 
solution is in slight excess the drop of the solution added to the 
tannin solution will turn it yellow, when the titration is finished. 
From the amount of lead taken and the number of cc. of 
molybdate solution used, the value of the solution in terms of 
sulphur may be calculated as follows: Suppose 0.3 gm. of lead 
was taken and 10 cc. of molybdate solution was used to pre- 
cipitate the lead. Then 1 cc. of molybdate solution is equiv- 
alent to 0.03 gm. of lead, or to 0.043913 gm. of lead sulphate, 
and as lead sulphate contains 10.56 per cent sulphur, its equiv- 
alent in S may be calculated by the factor 0.1056; the equiv- 
alent in this case being I cc. = 0.004637 -+. 

To determine sulphur in an ore or metallurgical product by 
this method the ore may be decomposed and the sulphur 
obtained in solution by fusion with caustic potash as described, 
by treatment with nitric acid and chlorate of potash and 
subsequent treatment with sodium carbonate as described, or 
yyy fusion in a porcelain or platinum crucible with a mixture 
of sodium carbonate and potassium nitrate. 

Where fusion with caustic potash is the method employed 
the fused mass is dissolved in hot water and filtered, hydrogen 
peroxide being added to the filtrate to oxidize the potassium 
sulphide. The solution is then heated and acidified with a 
slight excess of nitric acid. To the hot solution add an excess 
of a solution of lead nitrate, allow to stand until the precipi- 
tated lead sulphate settles and filter, retaining as much as 
possible of the lead sulphate in the beaker. Wash by decanta- 
tion with cold water until the washings no longer give a reac- 
tion for lead. Dissolve the lead sulphate in hot ammonium 
acetate, acidify with acetic acid and titrate with the standard 
ammonium molybdate solution. 

In case the nitric acid-potassium chlorate method is used, 


94 A MANUAL OF PRACTICAL ASSAYING. 


acidify the filtrate from the precipitated carbonates with a 
slight excess of nitric acid, boil out the carbonic acid, pre- 
cipitate the sulphuric acid with lead nitrate, and proceed as 
above. 

In case fusion with mixed carbonate of soda and potassium 
nitrate is the method adopted, to each gramme of substance 
taken add about 10 gms. of the mixed salts and fuse until the 
mass is liquid. Cool and dissolve the fused mass in hot water. 
Filter, acidify the filtrate with nitric acid, boil to drive out 
carbonic acid, precipitate the sulphuric acid with lead nitrate, 
and proceed as above. 

In all cases the reagents used should be examined for 
sulphur, as they are liable to contain sulphates. If pure re- 
agents cannot be obtained a blank analysis should be run, using 
the same quantity of reagents as in the regular analysis, and 
deducting the amount of sulphur found in the blank analysis 
from that found in the regular analysis. 

In the case of ores, etc., containing but a small percentage 
of sulphur, it is advisable to use a more dilute solution of 
-ammonium molybdate. Having made up the solution and 
standardized it as described, a solution of any desired strength 
can be readily prepared by drawing off a definite quantity of 
the standardized solution and diluting it with water to any 
desired strength. 

Iron and Steel.—The following rapid method for the 
determination of sulphur in iron and steel is quite accurate, 
and is extensively used in metallurgical works for technical 
determinations. Many modifications of the method have been 
proposed, but the two following are believed to be as good and 
rapid as any. The method was originally suggested by Kar- 
sten, and depends upon the principle that, if iron or steel is 
dissolved in dilute hydrochloric or sulphuric acid, H,S is 
evolved. The evolved H,S may subsequently be absorbed in 
a solution of a metallic salt. 

The cut, Fig. 13, shows the usual arrangement of appara- 
tus for carrying out the decomposition and absorption. The 
wash bottle 4 contains an alkaline solution of lead nitrate. 


SULPHUR. 95 


The generator G is used for generating hydrogen gas. The fun- 
nel-tube C is tightly connected with A. The small flask & 
serves as a condenser, and is supplied with an inlet-tube reaching 











Fics 13.* 


almost to the surface of a small amount of water in the bottom 
of the flask, a safety-tube / reaching just below the surface of 
the water, and an exit-tube connected with the first of the 
wide-mouthed bottles H. In each of the bottles / is poured 
from 20 cc. to 30 cc. of the absorbent solution, and sufficient 
water to fill them more than half full. 

Into the previously dried flask D are introduced 10 gms. of 
the drillings, free from lumps. The apparatus is now con- 





* From Blair’s Chemical Analysis of Iron and Steel. 


96 A MANUAL OF PRACTICAL ASSAYING. 


nected up, and a slow stream of hydrogen run through it until 
all the air is expelled, when the glass stop-cock S is closed and 
the supply of hydrogen is shut off by closing the glass stop- 
cock ZL. If the connections are all right the water in the 
safety-tube / will keep its level. When this is assured, dis- 
connect the tube C and fill the bulb with 50 cc. of strong 
hydrochloric acid and 50 cc. of water. Replace the tube C, 
turn on the hydrogen, and open the stop-cock S so as to allow 
the acid to flow into the flask D, drop by drop. When the 
acid has all run into D regulate the supply of hydrogen so that 
the gas will continue to pass through the solutions in the 
bottles H at the rate of 6 to 8 bubbles a second, and heat the 
contents of the flask D cautiously. Finally, heat the solution 
in the flask D to boiling, and boil for a few minutes. When 
the metal in the flask is completely dissolved, remove the 
source of heat and continue the current of hydrogen for about 
ten minutes, regulating its flow by means of the stop-cock Z, 
to prevent any reflux of the liquid in //, which might be caused 
by the cooling of D. Shut off the hydrogen, disconnect the ap- 
paratus, and wash the contents of the bottle into a beaker. 

Many methods of proceeding with the analysis, according 
to the absorbent! used, have been proposed, for which see “ The 
Chemical Analysis of Iron and Steel,” by Blair. 

Absorption by Ammoniacal Solution of Cadmium Sulph- 
ate.—T. T. Morrell* proposes to absorb the H,S in a solution 
of cadmium sulphate prepared by adding ammonia to a solution 
of sulphate of cadmium until the precipitate formed redissolves 
and the solution is clear. This solution is placed in the bottles 
H, H, and the analysis conducted as described. The precipi- 
tated cadmium sulphide is filtered off, and washed with water 
containing a little ammonia. The filter containing the pre- 
cipitated cadmium sulphide is now placed in a beaker contain- 
ing a little cold water, and sufficient hydrochloric acid to 
dissolve the precipitate is added. The sulphur may now be 
determined by titration with standard iodine solution. 





* Chemical News, Vol. XXVIII, p. 229. 


1 os 





SLE Td Pics Q7 


The method of determining the sulphur by standard iodine 
solution was first suggested by Elliott * and requires the fol- 
lowing solutions: 

Lodine Solution.—Dissolve 6.5 gms. of pure iodine in water 
with 9 gms. of potassium iodide, and dilute to 1000 cc. 

flyposulphite of Sodium Solution.—Dissolve 25 gms. of 
sodium hyposulphite in water, add 2 gms. of ammonium car- 
bonate, and dilute to 1000 cc. The addition of ammonium 
carbonate retards the decomposition of the sodium hyposul- 
phite. 

Starch Solution.—Place 1 gm. of pure wheat starch in a 
porcelain mortar and rub into a thin cream with water. Pour 
into 150 cc. of boiling water, allow to stand until cold, and 
decant the clear solution. A fresh solution should be prepared 
‘every few days. 

Bichromate of Potassium Solution.—Dissolve 5 gms. of pure 
potassium bichromate in water and dilute to 1000 cc. 

The bichromate solution is standardized as described in the 
determination of iron (Part II, Chapter XVI). When a solu- 
tion of potassium bichromate is added to a solution of potas- 
‘sium iodide containing free hydrochloric acid, iodine is liberated 
as follows: 


K,Cr,O, + 6KI + 14HCl = 8KCl + Cr,Cl, + 7H,O + 61. 


Or, I equivalent of K,Cr,O, (= 294.5) liberates 6 equivalents 
(= 761.1) of iodine. When a solution of hyposulphite of 
sodium is added to a solution containing free iodine the follow- 
ing reaction takes place: 


2NaHS,O, + 21 = 2HI-+ Na,5S,0,. § 


By adding a few drops of starch solution to a solution con- 
taining iodine, blue iodide of starch is formed, and colors the 
solution as long as it contains free iodine. When sufficient 
hyposulphite is added to such a solution to exactly combine 
with the iodine, the blue color disappears. Conversely, upon 


* Chemical News, Vol. XXII, peOr. 





05 A MANUAL OF PRACTICAL ASSA YING. 


the addition of a solution of iodine to a solution containing 
hyposulphite of sodium and a little starch, the blue color of 
the iodide of starch will disappear as fast as formed until all 
the triosulphate has been converted into tetrathionate, and 
then the slightest excess of iodine will give the solution a per- 
manent blue color. The same is true of a solution containing 
free H,S, the reaction being H,S-+ 21=2HI-+S. To stand- 
ardize the hyposulphite solution proceed as follows: Dissolve 
I gm. of pure potassium: iodide in 300 cc. of water, add 5 cc 
of hydrochloric acid, and then 25 c.c. of the standardized bi- 
chromate solution, which will liberate a known amount of 
iodine. Now add from a burette the hyposulphite solution 
until the blue color nearly disappears, add a few drops of starch 
solution, and continue the addition of the hyposulphite solu- 
tion until the blue color disappears entirely. The amount of 
iodine being known, the value of the hyposulphite solution is. 
readily calculated from the reading of the burette. Now 
measure off into a beaker 25 cc. of the hyposulphite solution,, 
dilute to 300 cc., add a few drops of starch solution, and run 
in, from a burette, standard iodine solution until the blue color 
is permanent. The value of the hyposulphite solution being 
known, that of the iodine solution can be readily calculated. 
(ee: Panel varC Nate 

Having prepared and standardized the solutions the actual 
determination is performed by titrating the solution containing 
the sulphur with the standard iodine solution in the manner 
just described. 

Absorption by Alkaline Solution of Lead Nitrate. 
—To prepare the solution pour a cold solution of nitrate of 
lead into a solution of potassium hydrate (1.27 sp. gr.), stirring 
constantly to dissolve the oxide of lead, which precipitates. 
Continue the addition of lead nitrate until a permanent pre- 
cipitate is formed. Allow the precipitate to settle, and siphon 
the clear liquid into a glass-stoppered bottle. To prevent the 
stopper sticking, coat it with a little paraffine. 

From 20 to 30 cc. of this solution is poured into the bottles. 
H, H, and water added until the bottles are more than half 





ai ey een ae! 


SULPHUR. 99 


full, The decomposition and absorption are conducted as 
previously described. When the operation is completed rinse 
out the bottle # (should the second bottle contain a precipitate 
this must be added to the contents of the first) into a beaker 
and filter, washing with hot water until the washings no longer 
give a reaction for lead when treated with a drop of acetic acid 
and potassium-chromate solution. Transfer the lead sulphide 
to a beaker, and dissolve in a little dilute nitric acid, being care- 
ful to use as little acid as possible. Add a slight excess of sul- 
phuric acid and boil. Dilute with hot water, add a slight 
excess of ammonia, and then a slight excess of strong acetic 
acid. The lead sulphate will be dissolved, when the solution is 
ready for titration with standard solution of ammonium molyb- 
date, after dilution to about 180 cc. with hot water. The lead 
is precipitated as a molybdate, and the end reaction obtained 
by means of a solution of tannin, in the manner described in 
the volumetric. determinations of sulphur and lead. Having 
the standard of the molybdate solution in terms of lead, its 
standard for sulphur may be obtained by the factor 0.1548. 

Generally the carbonaceous residue left after treating pig- 
iron with hydrochloric acid will contain sufficient sulphur te 
seriously affect the results of the analysis. Hence where an 
accurate determination of sulphur in pig-iron is required the 
examination of the carbonaceous residue should never be 
neglected when the evolution method is employed. To deter- 
mine the sulphur in this residue transfer the contents of flask 
D toa beaker and filter, using the filterppump and platinum 
cone and a strong filter-paper; wash thoroughly, first with a 
little dilute hydrochloric acid, and finally with water. Dry the 
residue on the filter, and determine the sulphur by some of the 
methods previously described, preferably by fusion. 





CHAPTE RIT, 


PHOSPHORUS (P). 


A number of different methods have been proposed for 
the determination of phosphorus in iron ores, pig-iron, steel, 
etc., but the volumetric method, as described below, and the 
standard gravimetric method are the only ones in general use 
at present in the United States. 

Volumetric Method.—This method, as Grieinally described 
by Mr. B. B. Wright,* and improved by Mr. F. A. Emmerton,t 
is applicable for phosphorus determinations in ores, steel, etc., 
and the writer believes is as rapid and accurate, provided the 
necessary precautions are observed, as any method which we 
have. It is rapidly being adopted by our iron and steel chem- 
ists as a standard method. 

Steels, Pig and Wrought [ron.—Dissolve 5 grammes of drill- 
ings in a dish (about 6 inches in diameter) in 75 cc. of nitric 
acid of 1.20 sp. gr., cover the dish with a watch-glass, placed 
on a glass triangle so that there is a space between the rim of 
the dish and the watch-glass, and boil down to dryness on the . 
sand-bath or hot iron plate. Heat on the plate or bath for 
about 30 minutes after the mass has gone to dryness, at the 
end of which time all the free acid should have been expelled. 
Remove from the source of heat, cool, and add 40 cc. of con- 
centrated hydrochloric acid, and place the watch-glass on the 
casserole. Heat gently until the iron goes into solution, and 
then boil down until all but about 15 cc. of the acid is driven 
off. The boiling down of the solution requires attention, as it 


—— 





* Transactions of American Institute of Mining Engineers, Vol. X, page 197. 
+ Ibid., Vol. XV, page 93. 
100 


PHOSPHORUS. IOI 


is necessary that the solution should be very concentrated, and 
at the same time there should be very little ferric chloride 
dried on the sides of the casserole, as this will be difficult to 
redissolve. Let the casserole cool, wash off the watch-glass 
With 40 cc. of concentrated nitric acid, allowing the acid to 
run down into the casserole. Cover the casserole with a glass 
funnel, and boil down to about 15 cc. in bulk. Remove the 
casserole from the source of heat, and move its contents so as. 
to moisten whatever crust may have formed on the sides. 
The solution is now practically free from hydrochloric acid, 
and should be diluted with water and washed into a 400-cc. 
flask, bringing the bulk of it to about 75 cc. Add strong am- 
monia, shaking thoroughly after each addition. Continue to 
add ammonia until the mass sets to a stiff jelly, and add a 
few cc. more. There should be a strong smell of ammonia in 
excess after shaking. Then add concentrated nitric acid, shak- 
ing well after each addition, until the solution begins to get 
thinner. After the precipitate has all dissolved, and the solu- 
tion shows a very dark color, add sufficient nitric acid to bring 
the solution to a clear amber color. The solution should now 
have a bulk of about 250 cc. Immerse a thermometer into the 
solution, and heat or cool carefully until it has a temperature 
of 85° C. When the solution has a temperature of 85° C. add 
40 cc. of ammonium-molybdate solution (prepared by dissolving 
100 grammes of molybdic acid in a mixture of 300 cc. of strong 
ammonia and 100 cc. of water, and pouring this solution into 
1250 cc. of nitric acid of 1.20 sp. gr.). Close the flask with a 
stopper, wrap it in a thick-warm cloth, and shake violently for 5 
minutes. This covering with a cloth is necessary, as the temper- 
ature of the solution must not vary much from 85° C. Collect 
the yellow precipitate on a filter, using the filter-pump to filter 
rapidly, and wash the flask and precipitate with a solution of 
ammonium sulphate [(NH,),SO, crystals, 25 grammes; H,SO,, 
conc., 50 cc.; H,O, 2500 cc.]. Dissolve the washed precipitate 
in ammonia. If a small portion of the precipitate should 
adhere to the sides of the flask it may be dissolved with a: 
portion of the ammonia used to dissolve the yellow precipitate 


ah . d 





{O02 A MANUAL OF PRACTICAL ASSA YING. 


on the filter. Place about 10 grammes of granulated zinc 
(the same as is used in the determination of iron; see Chap- 
ter XVI) in a 500-cc. flask, place the funnel containing the 
yellow precipitate in the neck of the flask, and wash the 
precipitate into the flask with dilute ammonia (1 in 4), using 
about 30 cc. A larger amount of ammonia than is absolutely 
necessary is to be avoided. After having washed with ammo- 
nia wash twice with water, and suck dry by means of the 
filter-pump. Pour the ammonia solution into a small beaker, 
reinsert the funnel in the flask, and pour the solution in the 
beaker through the filter again, washing the paper thoroughly 
with water after the ammonia solution has all run through, 
finally sucking the filter dry with the pump. Pour into the 
flask about 80 cc. of warm dilute sulphuric acid (1 in 4), and 
heat quickly until rapid solution of the zinc commences, and 
then gently stir for 10 to 15 minutes, at the end of which time 
the reduction of the molybdic acid is complete. Filter the 
liquid from the undissolved zinc through a large fluted filter, 
rinse the flask with cold water, pouring on to the filter. After 
these washings have run through, rinse the flask once more 
with cold water, pouring on to the filter again. The filtration 
should be rapid, so as to expose the solution to the air as 
short a time as possible. 

The filtrate is now ready for titration with a standard solu- 
tion of potassium permanganate. The permanganate solution 
is run in until the solution is colorless, it having been of a dark 
olive-green color before oxidation. One drop of permanganate 
solution should now produce a pink tint when the titration is 
stopped and the reading of the burette taken. A convenient 
strength to have the permanganate solution is I cc. = 0.0001 
sramme of phosphorus. Such a solution may be made by 
diluting the solution used for iron (Chapter III) with distilled 
water until I cc. = 0.006141 gramme iron. As 0.9076 time 
this value gives its strength in terms of molybdic acid = 
0.005574, and 1.794 per cent of this is its value in phosphorus 
= 0.0001. 








— a. oe 


ee =, 


: 
: 

‘ 
. 





PHOSPHORUS. . 103 


In order to insure good results with this method the above 
conditions as to temperature, etc., must be carried out. 

Dr. Drown* has proposed a method of effecting the solution 
of a pig-iron or steel which greatly lessens the time required. 
His method is as follows: Dissolve the weighed drillings in 
nitric acid of 1.135 sp. gr., and allow to boil one minute; then 


add potassium-permanganate solution until a precipitate of 


MnO, appears. Now add a few crystals of ferrous sulphate 


{should be tested for phosphorus, as the usual c. p. salt contains 


more or less. The phosphorus free salt can ‘be purchased of 
Baker & Adamson, Easton, Pa.) to dissolve’ the precipitated 
MnO,. Filter the solution into the flask, and add sufficient 


ammonia. When the solution clears up, add a few drops of 


ermanganate solution to insure complete oxidation, again 
Pp 5 | ; 


dissolving with ferrous sulphate if necessary. Precipitate with 
ammonium-molybdate solution, proceeding as above, and using 


the same precautions. 
A modification of the above method has been proposed by 
Handy,t which consists in the determination of the acidity 


of the molybdate precipitate in place of reducing the molybdic 


acid and titrating with permanganate. The following solutions 
are required: 

Standard Sodium Hydrate-——Dissolve 15.4 grammes of 
NaOH in 100 cc. of water, stir in saturated barium-hydrate 


solution until a precipitate of barium carbonate is no longer 


formed. Filter immediately, and dilute to two litres. 
Standard Nitric Acid — Make a stock solution of 200 cc. of 


acid (sp. gr. 1.42) in two litres of water. For approximate 
standard dilute 200 cc. of this solution to two litres. 


These two solutions should be made to‘agree cc. for cc., 
and had also best be brought to a strength of I cc., equal to 


0.0002 gramme of phosphorus. 


The sodium-hydrate solution is standardized by 0.1 gramme 
of pure molybdate precipitate obtained from acidified ammo- 


$$ 








* Transactions of American Institute of Mining Engineers, Vol. XVIII. 
+ Journal of Analytical and Applied Chemistry, Vol. VI, p. 204. 


104 A MANUAL OF PRACTICAL ASSAYING. 


nium or sodium phosphate, washed with one per cent nitric 
acid, and thoroughly dried at 100°C. The precipitate contains. 
1.63 per cent phosphorus. 

As an indicator, 0.5 gramme of phenolphthalein in 200 cc. 
of 95 per cent alcohol is used. Three drops of this solution 
are taken for each titration. 

The method is as follows: Dissolve 2 grammes of steel in a 
12-ounce Erlenmeyer flask in 75 cc. of nitric acid (sp. gr. 1.13),. 
and add 15 cc. of potassium-permanganate solution (5 grammes. 
in 1000 cc.) to the boiling solution. Boil until the pink color 
disappears. If brown MnO, separates, the oxidation is com- 
plete. Some irons and steels will require more permanganate, 
especially those high in carbon. Remove momentarily from 
the heat, add about 54, gramme of granulated sugar, and heat 
until the solution clears. Allow to cool for a few minutes and 
then add 13 cc. of ammonia (sp. gr. 0.90), pouring carefully 
down the sides. Agitate until the ferric hydrate is dissolved, 
and cool or heat to 85° C. Add 50 cc. of the molybdate 
solution, cork, wrap the flask in a towel, and shake for five 
minutes. Filter immediately, wash five times with a one per 
cent solution of nitric acid, and then five times with a one 
per cent solution of potassium nitrate. Place the filter and its. 
contents in the flask, add 10 to 20 cc. of the standard sodium- 
hydrate solution, and shake a few times to dissolve the precipi- 
tate. Add three drops of the indicator solution and titrate 
back with the standard nitric-acid solution. The titration 
must be performed quickly, and as soon as the precipitate 
is completely dissolved. 

Iron Ores.—Dissolve from 2 to 10 grammes of ore in hydro- 
chloric acid (sp. gr. 1.12), and proceed as above. The insoluble 
~ residue can be filtered off and fused with sodium carbonate 
(see Part II, Chapter I) if necessary, the fused mass being 
dissolved in dilute sulphuric acid, and the solution added to 
the nitric-acid solution. 

Coal and Coke.—The phosphorus will be found in the ash. 
Weigh out 10 grammes of the coal or coke, and ignite it over 
the blast-lamp or in the muffle-furnace until nothing but ash 


PHOSPHORUS. 105 


remains. Fuse the ash with sodium carbonate, and proceed as 
above. 

In the case of ores or pig-iron containing arsenic the arsenic 
will be precipitated, together with the phosphorus, upon the 
addition of the molydate solution, as above. In this case if 
the temperature of the solution is not above 25° C.,* when the 
molybdate solution is added the arsenic will remain in solution, 
whilst the phosphorus will be completely precipitated. As the 
steel metallurgists consider arsenic quite as detrimental to the 
quality of the pig as phosphorus this precaution is not usually 
taken. 

Gravimetric Method.—Proceed as above until the yellow 
precipitate is obtained, filtered, and washed, such care in regard 
to the temperature of the solution before adding the molyb- 
date solution being unnecessary in this case. Dissolve the 
yellow precipitate with ammonia as before, filtering into a 
beaker ; make the solution acid with dilute hydrochloric acid 
and then alkaline with ammonia in excess; cool, and when cold 
add 5 cc. of magnesia mixture. Allow to stand ina cool place 
for several hours with frequent agitation (see Part II, Chapter 
XXIV); finally filter, wash, ignite, and weigh as in the case of 
the determination of magnesia. 

The weight of the magnesia pyrophosphate obtained, mul- 
tiplied by 0.27928, equals the weight of phosphorus in the 
amount of substance taken. 

For comparative results and much valuable information 
regarding the determination of phosphorus in steel, see Trans. 
of the American Institute of Mining Engineers, meeting of 
October, 1895, Vol. XXV. 


nd 


* Transactions of the American Institute of Mining Engineers, Feb., 1893. 


CHAPTER IV. 


CARBON (C). 


FoR the determination of carbon in organic substances the 
reader is referred to works that treat of such determinations. 

The determinations of carbon in steel, pig-iron, etc., are 
about the only determinations of carbon which the metallur 
gical chemist will be called upon to make, except the determi- 
nation of carbon in fuels, for which the reader is referred to 
Part III, Chapter X. 

The carbon in steel, pig-iron, etc., usually exists in two 
conditions; that is, combined (as a carbide) and uncombined 
(graphite). Usually the combined carbon is all that is required. 
When the percentage of carbon in both conditions is required, 
the total carbon is determined in one portion and the com- 
bined carbon in another. The difference between the total 
amount of carbon and the combined carbon gives the graphite. 
Or the graphite may be determined, the difference between 
the amount of graphite found and the total carbon being the 
combined carbon. 

Many methods for these determinations have been pro- 
posed, but only those that are known to be good and are in 
general use will be given. . 

Total Carbon.—The following method, which was first 
proposed by Arthur Elliot,* is a modification of Rodger’s and 
Uligren’s methods. It is believed to be among the best in 
use.t Add to 2 or 3 grammes of borings or filings in a small 
beaker 50 cc. of a solution of neutral copper sulphate, prepared. 





* Chemical News, May, 1869. 
t+ American Chemist, October, 1871. Also Cairns, page 105. 
106 





CARBON. 107 


by dissolving the recrystallized copper sulphate (as sold by 
dealers) in water, adding a small quantity of copper oxide, boil- 
ing until the copper sulphate begins to crystallize, filtering out 
the excess of oxide, and concentrating the solution until it is 
completely crystallized. Dry the crystals by draining off the 
water, and pressing them between layers of bibulous paper, and 
dissolve them in water in the proportion of I part of salt to 5 
parts of water. 

After heating the solution of copper sulphate containing 
the iron about 10 minutes, by which means the iron is dissolved 
and the copper precipitated, add 20 cc. of a solution of cupric 
chloride (containing one part of salt in two parts of water) and 
50 cc. of concentrated hydrochloric acid, and heat to a point 
just below boiling, with frequent stirring until the precipitated 
copper is dissolved, leaving the carbon free. Filter out the 
carbon through a funnel made of glass tubing about five eighths 
of an inch in diameter, and drawn to a point at one end. Fill 
the point of the funnel up to the shoulder with broken glass, 
and place upon this a thin layer of ignited asbestos, pressing it 
gently against the walls of the funnel. Care should be taken 
not to make the layer of asbestos too thick or compact, as it is 
liable to become clogged by the carbon and render the filtra- 
tion very tedious. Filter off into a clean beaker, and should 
any carbon run through, as it is liable to at first if the asbestos 
layer is too thin, pour back the first filtrate into the filter. 
Transfer all of the carbon to the filter, and wash with. hot water 
until the washings no longer give a precipitate with silver ni- 
trate. After washing all of the carbon down from the sides of 
the tube, cut it off about an inch above the layer of carbon, by 
scratching the glass with a file, and pressing a red-hot giass 
against the cut. Then invert the part containing the carbon 
into the mouth of the decomposing flask of an apparatus sim- 
ilar to that described for determining carbonic acid * (see Part 
II, Chapter V), and blow the contents into the flask, avoiding 
the use of water by wiping out any carbon that may adhere to 





* See Cairns’ Quantitative Analysis, page 35. 


108 A MANUAL OF PRACTICAL ASSAYING. 


the glass with a little piece of ignited asbestos, and throwing 
this also into the flask. To the filtrate from the carbon add 4 
or 5 cc. of concentrated hydrochloric acid to prevent the for- 
mation of any precipitate of basic copper salt, and dilute with 
water until the fluid is transparent. If any carbon should have 
passed through the asbestos it can readily be seen in the trans- 
parent fluid. Should there be any filter it out through another 
filter of ignited asbestos and transfer it also to the flask. Con- 
nect the apparatus, and start the aspirator very slowly. After 
the aspirator has been working about 12 minutes, disconnect 
the absorption-tube and weigh it. Then connect again and 
start the aspirator very slowly again. After the aspirator has 
run a few minutes in order to partially exhaust the air in the 
apparatus, introduce through the funnel-tube about 4o cc. of 
the chromic-acid solution. 

This solution is prepared by dissolving 3 gms. of chromic 
acid in a little water and adding 30 cc. of pure concentrated 
sulphuric acid. This should be heated to incipient boiling 
and then cooled. When cold it is ready for use. 

After adding this solution close the stop-cock of the funnel. 
tube and heat slowly up to boiling. After the acid boils re- 


move the heat, put on the guard-tube, open the stop-cock of 


the funnel-tube, and aspirate slowly until the absorption-tube 
is cool. After it is thoroughly cooled weigh it, and from the 
increase in weight due to the carbonic acid (CO,) calculate as 
follows: The weight of the carbonic acid multiplied by 0.27273 
equals the weight of carbon. 

In place of the copper sulphate and copper chloride, the 
double chloride of copper and ammonium may be used. The 
same precautions should be observed as in the determination 
of carbonic acid by direct weight. Some chemists prefer to 
burn the carbon obtained in the above manner in a current of 
oxygen in a piece of combustion-tubing, absorbing the resulting 
carbonic acid in an absorption-tube similar to the one used 
above, or in a potash bulb.* (See Part III, Chapter X.) 








* American Chemist, Vol. VI, September, 1875. 


CARBON. 109 


Graphite.—The best and safest method is that described 
by Cairns * as follows: Dissolve from 2 to 3 grammes of gray 
pig-iron or from 4 to 5 grammes of white iron, steel, etc., in 
dilute hydrochloric acid and boil for half an hour, filter 
through asbestos as described for total carbon, wash with hot 
water until all acid is washed out, then with a strong solution 
of potassium hydrate, which will remove silica; afterwards with 
hot water to wash out any potassium carbonate, of which the 
potassium hydrate is apt to contain some; then with alcohol 
(which will remove hydrocarbons), until the alcohol runs 
through the funnel colorless. Again wash with a little hot 
water, then with ether, until it runs through colorless, in order 
to displace the water and remove another class of hydrocarbons 
which the alcohol may have failed to reach. It is well, finally, 
to wash with a little hot water (particularly if the ether used is 
not perfectly pure), in order to keep the graphite from adher- 
ing to the walls of the funnel, when blown into the decompos- 
ing flask, being careful to remove any excess of water by 
gently blowing through the funnel. After the graphite is 
thoroughly washed it is transferred to the decomposing flask, 
and oxidized with chromic and sulphuric acids, in precisely the 
same manner as in the determination of total carbon. 

The objection to this method is the time required to filter 
and wash, the washings with potassium hydrate being ex- 
tremely tedious. 

Eggerz’s modified method + is as follows: In a beaker of 
Peeeco capacity mix 4 cc. of sulphuric acid and 20 cc. of 
water, and when the heat produced by the combination of the 
water and the acid has entirely disappeared, shake 2 grammes 
of the finely powdered pig-iron into the dilute acid, and boil 
for half an hour. (For steel and wrought iron not less than 3 
grammes should be taken, and the acid for solution should be 
increased in proportion.) The solution is then evaporated 
until it measures 18 cc., allowed to cool to the temperature of 
50° C., and 4 cc. of nitric acid (of 1.20 sp. gr.) added; boil for a 





* Cairns’ Quantitative Analysis, edition 1881, page 114. 
+ Crook’s Select Methods, pages 79 and 80. 


IIo A MANUAL OF PRACTICAL ASSAYING. 


quarter of an hour, and allow to evaporate on a water-bath 
until on holding a watch-glass over the beaker there occurs on 
it no perceptible condensation. To the dry mass add 30 cc. 
of water, and 5 cc. of hydrochloric acid 1.16 sp. gr.; boil fora 
quarter of an hour, and add more hydrochloric acid if there 
appears to be anything besides silica and graphite undissolved. 
The insoluble silica and graphite are thrown on a filter (which 
has been dried at 100° C. and carefully weighed), washed with 
cold water until the washings give no reaction for iron when 
tested with potassium ferrocyanide, then washed with boiling 
water containing 5 per cent of nitric acid. The silica and 
graphite are then dried on the filter at 100° C. and weighed, 
ignited in a porcelain crucible, and the weight carefully taken. 
The difference between the weighings before and after ignition 
gives the amount of graphite. 

Combined Carbon.—Dr. Eggerz, of the Swedish School of 
Mines, first proposed a method of determining the combined 
carbon in steel, etc., by comparing the color of a solution of 
the iron or steel under examination with that of a solution of 
another sample of which the carbon percentage was known. 
This method is based upon the fact that when steel is dissolved 
in dilute nitric acid, and heated until the separated flocculent 
carbonaceous matter goes into solution, the liquid assumes a 
brown color proportionate to the amount of combined carbon 
present. This method has been modified from time to time 
by different chemists so that we have at present a method 
which is not only rapid, but extremely accurate provided the 
proper precautions are observed. A number of standard 
solutions for comparison have been proposed, but the best 
and safest method is to run a standard, together with each set 
of determinations, using a steel or iron in which the per- 
centage of combined carbon has previously been accurately 
determined. This standard steel should be as nearly like the 
samples to be treated as possible, both as to chemical com- 
position and mechanical treatment. Treat the standards and 
samples to be tested exactly alike in working, the same 


CARBON. III 


amounts being taken.* Drillings are preferable to filings, as 
they are less liable to contain foreign matter, and, being 
coarser, dissolve more slowly. Fine particles of steel, rich in 
carbon, dissolve so rapidly that, unless special precautions are 
taken to keep the solution cold, some of the carbon is oxid- 
ized and given off as a gas. From 0.1 to 0.2 gramme are 
taken for analysis, one tenth being the usual amount in the 
case of steels. | 

The weighed portions are best dissolved in perfectly dry 
(so that no particles will stick to the sides) test-tubes six 
inches long and about five eighths of an inch internal diameter, 
the sample being placed in the test-tube, which is then im- 
mersed in cold water and the dilute nitric acid then slowly and 
steadily poured on. A very convenient form of apparatus is a 
beaker or other vessel about 7 inches high, which is half filled 
with cold water and covered with a perforated tin plate, 
through the holes of which the tubes are placed and thus 
steadied. Nitric acid (free from organic matter, nitrous fumes, 
and chlorine) of about 1.20 sp. gr. is used to effect solution. 
The ordinary c. p. nitric acid is 1.40 sp. gr., and by diluting 
this one half with distilled water an acid of very nearly 1.20 sp. 
er. is obtained. It should be kept in a dark glass-stoppered 
bottle and ina dark place. The following amounts of dilute 
acid for one-tenth gramme of steel give good results: up to 
0.20 per cent’ carbon, 2 cc. of acid; from 0.20 up to 0.50 per 
Seltecatpol, 4 Cc.; from 0.50 per cent up to I.00 per cent 
Pe ivanwaecc., 1-00 per cent upto 1.75 per cent, 6cc.; over 1.75 
Memecnveo! carbon, 8 cc. The most convenient method of 
adding the acid is to let it run in from a graduated burette 
provided with a glass stop-cock. 

The solution must not be heated until all action has ceased 
in the cold, when the cold water in which the tubes are im- 
mersed is rapidly brought to a boil and boiled for 15 minutes 
for soft steels under 0.15 per cent carbon, for 20 minutes if 


* Transactions of American Institute of Mining Engineers, Vol. XII, page 
303. 


FIZ A MANUAL OF PRACTICAL ASSAYING. 


between 0.15 and 0.30 per cent carbon, for 30 minutes if be- 
tween 0.30 and 0.80 per cent carbon, and 45 minutes if above 
0.80 per cent carbon. The boiling temperature is usually 
maintained, although for special reasons other temperatures 
are often used, the essential point being to always maintain the 
same temperature in all cases where fixed standards are used, 
and to treat the standard and the steel under examination at 
exactly the same temperature where standard steels are used 
for comparison, as is recommended here. Sometimes a reddish- 
yellow deposit of nitric acid and ferric oxide forms on the sides 
of the tubes and renders the solution turbid; in such cases a 
low temperature of about 70° C. is preferable. The water-bath 
in which the tubes are heated may be provided with a ther- 
mometer, and the evaporation of the water may be prevented 
by the addition of paraffine. The ceasing of the evolution of 
the fine bubbles of gas from the clear solution is an indication 
of the completion of the solution. The tubes should be shaken 
from time to time during the heating, and the iron salt should 
not be allowed to dryon the walls of the tubes. The color 
solutions during the entire operation must be kept out of the 
direct rays of the sunlight, as it rapidly fades them. The color 
fades more rapidly after dilution with water than it does in the 
strong acid solution. After heating, the tubes may be cooled 
rapidly by plunging into cold water. If the percentage of car- 
bon is high (about 1.00 per cent) the solution should not be 
allowed to stand any length of time before comparison; if the 
carbon is low they may be allowed to stand at least two hours. 
However, it is best to cool quickly. After the solution is com- 
pleted it must be diluted with at least its bulk of water to get 
rid of the tint of oxide of iron. The color solution, after heat- 
ing, cooling, and diluting with distilled water, can be filtered 
from the graphite, etc., through an ordinary dry filter-paper. 
The quantity of water added, including the distilled water used 
for cleaning the test-tube, must be at least equal to the quantity 
of nitric acid used, and the total volume must never be less 
than 8 cc. when it is to be compared with the standard solution. 
The solution is filtered directly into a burette or tube for com- 


CARBON. 113 


parison. Tubes of about one half an inch in internal diameter 
and 30 cc. capacity are preferable, and it is generally preferable 
to calibrate the tubes by means of an accurately calibrated 
burette, as those which are purchased calibrated often show 
errors of considerable importance. The tubes used for the 
standard and the different determinations should be of exactly 
the same internal and external diameters, and of colorless glass, 
and provided with mouth-pieces at the upper ends. The 
method of procedure is as follows: Suppose the standard steel 
contains 0.75 per cent carbon; if we dilute the solution in the 
tube (thoroughly mixing after each addition of water) to 15 
cc., then each cc. will contain 0.05 per cent of carbon. We 
now dilute the solution of the steel in which the carbon is to 
be determined with distilled water until its color exactly cor- 
responds with that of the standard steel, and then take the 
reading of the height of the liquid. One minute should be 
allowed for the liquid to run down the walls of the tube before 
taking the final reading. Suppose it reads 16 cc.; then, as each 
cc. contains 0.05 per cent carbon, 16 will contain 0.80 per cent. 
In comparing the colors it is usual to hold a piece of thin, clear, 
white paper behind the tubes. To most eyes the left-hand 
tube will appear slightly the darkest. A good plan is to match 
the colors so that either tube, as it is reversed, will appear 
darkest when it is placed to the left. This appearance can be 
corrected by holding the tubes a little tothe right. A.E. Hunt 
recommends the use of a camera-shaped box, painted black 
inside, open at one end to look into, and having a frame hinged 
at the bottom which is covered with thin white paper to form 
a background for the tubes. Near this end have an opening 
in the frame and a gutter in the bottom to allow the tubes to 
be placed. Hunt says: “This arrangement I have found 
especially useful in the night-time, when I used a fixed Bunsen 
gas-burner in which a bead of carbonate of soda on a platinum 
wire gives a monochromate flame. It is placed in such a posi- 
tion as to have the rays reflected, by means of the hinged frame 
of paper at the back, upon the tubes. I have been enabled in 
this way to read color carbons with much ease. In fact, I prefer 


114 A MANUAL OF PRACTICAL ASSAYING. 


this means of comparison to daylight, as the light is always. 
under control, and no outside rays interfere with lights and 
shadows.” It is preferable, especially where color-carbon 
analyses are only occasionally made, to use color standards of 
steel with each set of analyses in the manner described. Where 
many samples are to be tested every day, as in a Bessemer- 
steel works, it is much more conveniently and rapidly done by 
simply matching the diluted test with a rack of permanent 
standards representing different percentages of carbon. Per-. 
manent standards of organic substances, as burnt sugar, burnt 
coffee, etc., are not satisfactory.* Eggerz describes a mixture 
of chlorides of iron, cobalt, and copper, which is highly recom- 
mended by a number of chemists for the preparation of per- 
manent standards. By adding to the neutral chlorides water 
containing 1.5 per cent hydrochloric acid for the chloride of 
iron and o.5 per cent hydrochloric acid for the two other 
chlorides, solutions can be prepared of a strength correspond- 
ing to O.o1 gramme of metal per cubic centimetre. Then 8 cc. 
of the iron solution are mixed with 6 cc. of the cobalt solution 
and 3 cc. of the copper solution, and about 5 cc. of water con- 
taining 0.5 per cent hydrochloric acid are added to the mixture. 
At atemperature of 18° C. this solution shows the same color 
as a solution of steel in dilute nitric acid corresponding to 0.1 
carbon per cubic centimetre. The solution may be afterwards. 
diluted with water containing 0.5 per cent hydrochloric acid to. 
any standard color required. The addition of water is almost 
directly proportional to the percentage of carbon. The standards. 
thus proposed should always be standardized by comparison 
with solutions of steel containing a known amount of carbon. 
Frequently, as in the case of the open-hearth steel process, 
only a few minutes can be allowed for the determination of 
the carbon in tests taken from the furnace. For samples. 
where the carbon is below 0.25 per cent a quite accurate de- 
termination can be made by dissolving 0.10 gramme of the fine 
drillings in 2 cc. of 1.20 nitric acid in a test-tube, and by treat- 





* Transactions Institute of Mining Engineers, Vol. X, p. 186. 


CARBON. 115 


ing the standard in the same manner and at the same time in 
a similar tube as regards diameter, color, and thickness-of glass, 
and then judging of the variations of color at the moment of 
complete solution and before the carbon begins to separate 
out. The drillings should be of about the same degree of fine- 
ness, so that they will dissolve in about the same time. When 
the carbon is above 0.25 per cent the drillings are dissolved in 
4 cc. of dilute nitric acid, which has previously been heated in 
the water-bath to a point below boiling, and as soon as the 
violent ebullition has ceased, boiled by holding the tubes over 
a burner protected by a piece of wire-gauze. It takes about 4 
or 5 minutes’ boiling to effect complete solution, and a few 
minutes to cool sufficiently in cold water. When the solutions 
are ready to decant into the calibrated tubes, dilute and com- 
pare. The color solutions prepared in this way are much 
darker than when prepared in the usual way and boiled for 
several minutes. For this quick work a number of weighed 
portions of standard drilling are prepared beforehand. 


CHAPTER V;z 


CARBONIC ACID (CO.). 


CARBON dioxide (usually called carbonic acid) may be deter- 
mined by loss of weight upon heating, provided no other vola- 
tile matter (such as water) is present, loss upon treatment with 
acids, or it may be determined by direct weight. The latter 
method is preferable, and is more satisfactory in all cases. 

The determination by direct weight consists in driving off 
the carbonic acid, by means of heat or decomposition of the 
substance by acids, conducting it over into a weighed absorp- 
tion apparatus. The increase in weight of the absorption ap- 
paratus represents the weight of the carbonic acid driven off. 
When heat is used as the decomposing agent the apparatus 
described for the determination of water by direct weight 
(Chapter VI) may be employed. The apparatus is the same 
as before, with the exception that between the calcium-chloride 
tube and the last U-tube (the one connected with the aspirator) 
is connected a suitable apparatus for the absorption of the car- 
bonic acid. A calcium-chloride tube filled with small lumps 
of freshly prepared soda lime is a very good form of absorption 
apparatus, or a Liebig potash bulb containing a strong solution 
of caustic potash may be used. The left-hand end of the com- 
bustion-tube should also be connected with a similar absorption 
apparatus in order that all air which enters the combustion-tube 
may be free from carbonic acid. The substance is introduced 
into the combustion-tube and the analysis performed in the 
same manner as described for water, the increase in weight in 
the absorption apparatus representing the carbonic acid (CO,) 
absorbed. In the case of white-lead and similar substances the 


water and carbonic acid may be determined in this way by one 
116 


CARBONIC ACID. L17 


operation. When acids are used as the decomposing agent the 
form of apparatus will be slightly different. In place of the 
combustion-tube a decomposing flask is used. A wide-necked 
class flask of about 300 cc. capacity, provided with a tight rub- 
ber stopper with three perforations, answers the purpose. In 
one of the holes is fitted a piece of bent-glass tubing, provided 
with a glass stop-cock or a piece of rubber tubing and a pinch- 
cock. The tube should enter the neck of the flask about one 
inch, This will be designated a. A funnel-tube provided with 
a glass stop-cock should enter the flask through the second hole. 
The bottom of the funnel-tube should reach to within about 
an inch of the bottom of the flask so that its end will be covered 
by the fluid in the flask. This will be designated 6. Through 
the third hole pass a piece of bent-glass tubing so that its end 
is flush with the bottom of the rubber stopper. To a attach 
a chloride of calcium tube filled with soda-lime, close the stop- 


\ 
: 


eK 


























\ an ae 
AS eee. laa): Va 
E USS é 
C - : 
Fic. 14. 


cock of 4,and attach toca series of three U-tubes partially 
filled with pumice and sulphuric acid, as before. To the last 
U-tube of the series attach a calcium-chloride tube filled with 
soda-lime, or similar absorption apparatus, and to the right- 
hand end of the tube attach another U-tube filled with pumice 
and soda-lime to prevent moisture finding its way back. To 
this last U-tube attach the aspirator, and start slowly so as to 


118 A MANUAL OF PRACTICAL ASSAYING. 


pass a current of air through the apparatus. To perform the 
analysis, disconnect the absorption-tube, and after carefully 
weighing reconnect it. Into the decomposing flask introduce 
about 25 cc. of water and then a weiglied amount of the sub- 
stance. Replace the stopper and close the stop-cock of a and 
6. Start the aspirator and introduce into the funnel at 6 
some strong sulphuric acid, turning the stop-cock of 6 gradually, 
so as to allow a small amount of acid to run into the flask. 
The aspirator should be run slowly so as to passa slow current 
through the apparatus, and the acid should be added slowly 
by means of the stop-cock 6, After sufficient acid has been 
added and all ebullition of gas has practically ceased, gradually 
heat the contents of the flask by means of the flame of a lamp 
or burner. Open the stop-cock a and continue to run the aspi- 
rator until the volume of air in the apparatus has been changed 
four or five times. Disconnect the absorption-tube and weigh. 
The increase in weight represents the carbonic acid driven off 
and absorbed. 





CHAPTER VI. 
WATER (H.0O). 


WATER may exist in two states in ores, etc., uncombined 
{moisture) and combined (water of crystallization). 

Moisture.—To determine the moisture in an ore, heat a 
weighed amount of the pulverized sample at 100° to 105°C. in 
a weighed porcelain crucible to constant weight. The loss in 
weight represents the moisture expelled in drying. A hot-air 
bath provided with a thermometer is the most convenient ap- 
paratus in which to perform the drying. 

In the case of coal, coke, etc., it is advisable to raise the 
‘temperature of the bath to about 115° C. 

In a metallurgical works the sample will usually be given to 
the chemist with the moisture expelled, it having been previ- 
‘ously dried by steam at the sampling-works, where the percent- 
age of moisture in the lot or shipment of ore is determined. A 
good method to be pursued at a sampling-works is as follows: 
One or more samples of a little over a pound each are taken 
from each car or wagon load of ore as it comes into the yard, cate 
being exercised to take for a sample the fine and coarse ore in 
about the same proportions as they exist in the car or wagon 
load, and to take the sample from different parts of the load. 
The lumps of ore are then broken up and one pound of the 
‘sample weighed out into the ordinary assay-pan. A good plan 
of keeping track of the samples is to write the number of the 
car on a piece of wood and stick it in the sample. A conven- 
ient drier can be made of boiler-iron. It should be several feet 
in length and at least 3 feet in width, if many determinations 
are to be made in the course of the day as is the case in most 


smelting-works, and about 6 inches in depth. The joints 
119 


120 A MANUAL OF PRACTICAL ASSAYING, 


should be steam-tight. The exhaust-steam from the engine is. 
conducted into the box and heats the iron plate upon which 
the sample-pans are placed. A good plan is to take the samples. 
in the afternoon, and, after weighing out, let them dry over 
night on the dryer. The Fairbanks Scales Company make a 
very convenient scales for this purpose. The top of the beam 
is graduated into ounces and the bottom into percentages. 
When the weight is on the end of the beam the scales will 
weigh one pound. After drying, transfer the sample to the 
pan of the scales and weigh; the indicator of the weight will. 
show the percentage of moisture lost. From the percentages. 
thus found calculate the total pounds of moisture in the lot of 
ore. 


Combined Water.—The method to be pursued will depend 


~ on the character of the substance. When the substance con-- 


tains no volatile matter which is driven off by heating except 
water, and does not undergo oxidation upon heating, heat to. 
redness over the flame of a burner or in the muffle-furnace and 
weigh. Heat and weigh again, and repeat the operation until 
the crucible and contents no longer lose weight by being: 
heated. 

When volatile matter other than water is present, as for 
example white-lead, which contains both water and carbonic 


acid, a direct determination of the water is necessary. The — 


following method will serve for most substances: 

Prepare a piece of combustion-tubing, about 12 inches in 
length, and to the left-hand end attach a suitable drying ap-. 
paratus so that all air entering the tube will be perfectly dry. 
A very good form of drying apparatus can be made of three U-. 
tubes about 5 inches in length, and nearly filled with small 
lumps of pumice. Then pour into each tube sufficient con- 
centrated sulphuric acid to fill the tubes about one third, pour- 
ing the acid over the pumice, so as to saturate it. The U-tubes. 
are connected together and to the combustion-tube by perfo- 
rated rubber stoppers and pieces of glass tubing. All joints. 
can be made perfectly tight with paraffine. To the right-hand 
end of the combustion-tube attach a calcium-chloride tube: 


WATER. I2I 


filled with small lumps of freshly prepared calcium chloride. 
To prepare the calcium chloride, break it into small lumps and 
heat to redness in a clay crucible. After cooling ina dry place 
it is ready for use. To the other end of the calcium-chloride 
tube attach a U-tube filled with pumice and sulphuric acid, as 
before, to prevent any moisture finding its way back. When 
the apparatus is all connected attach the last U-tube to the 
aspirator (the filter-pump makes a very convenient aspirator) 
and start a slow current of air through the apparatus. Gently 
warm the combustion-tube, by holding the flame of a burner 
under it, to expel any moisture there might be in the tube. 
After the current of air has passed through the apparatus for 
about 15 minutes, disconnect the calcium-chloride tube and 
weigh it carefully. Now introduce one or more grammes of 
the substance into the combustion-tube by means of a weighed 
platinum or porcelain boat, reconnect the calcium-chloride tube, 
and start the aspirator slowly. Heat the substance in the boat 
by means of a good burner, gradually bringing to redness, and 
continue to heat for some time, finally moving the flame along 
the combustion-tube to expel any moisture that may have con- 
densed on its sides. Cool and whilst cooling continue to run 
the aspirator. Disconnect the calcium-chloride tube and weigh 
it. Its increase in weight will be due to the moisture absorbed 
by the calcium chloride. From the amount of substance taken 
caiculate the percentage of water. 


GHAR II Re sy.i 


GOLD (Au) AND SILVER (Ag). 


AS gold and silver are generally associated together in ores, 


and as their methods of assay are similar, they will be treated 


of together in the following pages. 

Gold is universally determined and weighed as metallic 
gold. In ores it is universally determined by fire-assay, the 
assay occasionally being preceded by treatment of the ore with 
acids (Part III, Chap. IV), and occasionally being preceded by 
roasting of the ore. Silver is determined in the same manner, 
the ore or furnace-product sometimes undergoing treatment 
with acids or roasting previous to assay. Alloys, such as silver 
bullion, are treated by special methods, either fire-assay or 
volumetric assay in the wet way (Part III, Chapters II and 
Tih: . 

The fire-assay is general in its application, and is the 
method universally adopted for estimating the gold and silver 
contents of ores, mattes, slags, etc. The results are not abso- 
lutely’ accurate, as there is necessarily a loss of both gold 
and silver in fusion, scorification, and cupellation. The most 
serious loss takes place in cupellation, the precious metals 
being carried into the cupel and off in the fumes. On the 
other hand, the gold and silver buttons may be contaminated 
with certain impurities of the ores under treatment, and the 
silver buttons with oxides of silver and lead, and the final gold 
beads with silver. When necessary, corrections may be made 
for these differences, but such corrections are not usual in 
commercial work, except in the assay of gold bullion and 
silver bullion. 


The fire-assay consists essentially in the collection of the 
f I22 


GOLD AN DT SLL V LER. 123 


gold and silver in a button of metallic lead either by scorifica- 
tion (scorification method) or by fusion (crucible method). 
The lead button is then freed from the adhering slag by ham- 
mering on an anvil, and is finally hammered into the form of 
a cube when it is ready for cupellation. 

Both the scorification and crucible methods are extensively 
used, the general practice in Colorado being to determine the 
silver in two or more portions of the ore by scorification and 
the gold in two or more portions by crucible assay. On the 
Pacific coast the crucible method is the favorite one for both 
gold and silver. Both methods have their advocates, but we 
believe the Colorado practice is preferable, as most ores will 
yield higher silver results by scorification and higher and more 
uniform gold results by crucible assay. The reason that the 
crucible method gives better results on gold is owing to its 
allowing larger quantities to be taken for assay, and hence a 
larger button of gold is obtained for weighing than in the 
scorification-assay, where only a small quantity can be taken, 
resulting in a small button, which introduces a source of error 
in the weighing and calculation of results. This can be obvi- 
ated by running a number of scorifications and combining the 
buttons in parting. 

Scorification-assay.—The quantity of ore taken for assay 
will depend upon the grade and character of the ore and the 
size of the scorifiers on hand. The amounts usually taken are 
zy or 7%, assay-tons. The table on the next page gives the 
charges upon the basis of =, A. T. ton. 

Litharge added to the assay as a cover, in the case of 
pyrites and mattes, helps the assay. A mixture of equal parts 
of sodium bicarbonate and nitre effects the same results. 

Arsenical and copper pyrites, speiss, and copper mattes 
containing a high percentage of copper are preferably assayed 
by special method. 

On most ores a charge consisting of ore 7, A. T., test-lead 
40 grammes, and borax-glass as required, after scorification 
commences, gives good results. 

In case an insufficient quantity of lead or borax-glass has 


I24 A MANUAL OF PRACTICAL ASSA YING. 





Drege tM creat ieaatel Barua Remarks. 

Cr ALCM AT ek. s's pois ios 15-18 up to 0.5 
Galena with blende 

BOG IDV Cte ks, ws 20-35 0.4-0.& 
PION PY TilGane eso - x 30-45 0.3-0.8 
Arsenical pyrite... 45-50 o.3-1.5 | High temperature. Addition of 

litharge helps assay. 

(STAY COPPET i wiles 5: 35-48 0.3-0.5 | Low temperature. 
BSlende. sa 2. 's clers 30-45 0.3-0.6 | High temperature. Addition of 


oxide of iron helps assay. 
Copper ores and 


MALES (Sess oe ose 35-40 0.3-0.5 | Low temperature. If necessary, 

the button should be rescorified 

Lead mattes....... 25-35 O.5-1.0 with lead. 

Furnace accretions. 25-50 0.3-1.5 

LONUTICGS ahs w oc os 50 Ong Add a cover of litharge and re= 
scorify the button. 

SSILICLOUSS bts a str iais 25-30 

PSASICS on wists ccche' ete aie 25-30 0.5-2.0 | If the ore contains much lime or 


magnesia the addition of sodium 
carbonate helps the assay. 
Basic with Barium 
sulphate.5% <2, -. 25-30 0.5-1.5 | Addition of sodium carbonate 
helps the assay. 
Lead carbonate.... 10-15 up to 0.5 


SPCISSe. ssa teeaite Pug 30-60 o.3-0.5 | High temperature. Rescorify the 
button with lead if necessary. 


been added, the deficiency can be made up by adding, after 
the scorification has commenced, lead in the form of sheet-lead 
rolled into a compact piece, or borax-glass wrapped in a small 
piece of tissue-paper. If the test-lead or sheet-lead contains 
silver (some silver is always present), the amount which it 
contains should be determined, and the amount present in the 
weight of test-lead or sheet-lead used in the assay should be 
deducted from the weight of the resultant button. 

To determine the silver in the test-lead, scorify Ioo grammes 
of test-lead with borax and cupel the resulting button. 


ee! e 


GOLDVAND SILVER: 125 


Care should be exercised to use the proper amount of 
fluxes, so that the resulting button will be of the proper size 
(8 to 12 grammes in weight). If the button is too large, it may 
be reduced to the proper size by further scorification with test- 
lead and borax-glass. This will frequently happen with ores 
containing much copper. It is better to reduce too large 
a button by scorification rather than to cupel the button 
directly, as the loss of precious metals is less in scorification 
than in cupellation. In case the button is hard or brittle, it 
should be rescorified, with the addition of test-lead. In this 
case care should be exercised in removing the button from the 
slag that no particles of the button be lost. The fluxes are 
usually measured in place of weighing them out. A very con- 
venient tool for measuring out the test-lead is the adjustable 
measure which sportsmen use for measuring the charges of 
shot with which they load shells. After some experience the 
assayer will be able to guess at the weight of the borax-glass 
sufficiently close. 

One half of the test-lead is placed in the scorifier, the care- 
fully weighed ore added and mixed with the lead by means of 
a steel spatula. The balance of the test-lead is now added as 
a cover and the borax-glass placed on top. The scorifiers are 
placed in the muffle and the door closed. The door is kept 
closed until scorification commences, which is indicated by the 
mass subsiding and a ring of slag forming around the surface 
of the metallic lead. As the scorification proceeds the ring of 
slag grows larger, until it finally closes over the surface of the 
lead. The muffle should now be closed and the heat raised for 
a few minutes, in order to insure the’slag being perfectly fluid ; 
the scorifier is then removed from the muffle and its contents 
poured into the scorifier mould. As soon as the assay is cool, 
which takes but a few minutes, it is removed from the mould 
and the slag removed by pounding on the anvil with a light 
hammer. The lead button is hammered into the form of a 
cube, when it is ready for cupellation. The slag should be 
perfectly fluid. The lead should collect in one malleable but- 
ton. The buttons should be weighed separately, and should 


126 A MANUAL OF PRACTICAL ASSAVING. 


not differ by more than 0.5 oz. per ton on ore assaying 100 ozs. 
per ton. 

The calculation of results is as follows: Suppose 74 A. T. 
taken for each scorification, four scorifications being made. 
The combined weights of the four buttons before parting is. 
42.5 milligrammes. The weight of the gold button from the 
four assays is 3.8 milligrammes: then 42.5 — 3.8 = 38.7 = 


weight of silver, and 38.7 x 4% =096.75 oz. silver, and 3.8 x 12- 


= 9.5 oz. gold per ton of Bese Ibs. If the gold is detente 
separately by crucible-assay it is unnecessary to part the buttons. 
from the scorification-assay, except as a check. In order to 
obtain the weight of the silver, the amount of gold as found 
by crucible-assay is deducted from the amount of silver and 
gold as shown by the scorification-assay. 
Crucible-assay.—The amounts of ore usually taken for 
assay is $4 A. T. or 1 A. T., depending upon the grade of the 


ore, the aoe of the Seca and whether the fusion is per- 


formed in the wind-furnace or the muffle-furnace. If the fusion 
is performed in the muffle-furnace $ A. T. will usually be taken, 
as a larger quantity would involve the use of an awkward-sized 
crucible for the muffle. In Colorado the fusion is usually per- 
formed in the muffle, and this practice is to be reeommended 
on account of the cleanliness and the greater facility with which 
the heat can be regulated as compared with fusion in the wind- 
furnace. 

In making up a charge the object to be attained is to 
produce a fluid slag which will permit of a perfect separation 
of the lead into a button of the proper weight (10 to 20 
grammes), to drive the impurities in the ore into the slag and 
not into the lead, and to collect all the gold and silver in the 
lead button. The proper fluxes and the amounts of each to be 
_added will depend upon the mineral composition of the ore. 

If the ore is in lump form its mineral composition can be 
determined by simple eye-inspection or a few blowpipe tests. 
If in the form of powder, place about 0.2 gramme of the ore on 
a large watch-glass, add water, and van by rotating and tapping 
the glass to separate the different minerals. An inspection of 


GOLDWANE. SILVER: 127 


the vanned sample with a magnifying-glass will usually show 
the mineral composition. 

In making up a charge it must be remembered that sulphur, 
arsenic, and antimony act as reducing agents, and that ferric 
oxide and carbonate act as oxidizing agents. Nitre acts as an 
oxidizing agent, but its use is objectionable for the following 
reasons: Unless a large-sized crucible is used, and care is exer- 
cised to heat the crucible and its contents gradually, during 
fusion loss is liable to occur from deflagration and the contents 
of the crucible boiling over. The use of nitre also requires that 
the reducing power of the ore be known. If the composition 
of the ore is known (as regards S, As, and Sb), its reducing 
power can be calculated. If its composition is unknown, its 
reducing power may be determined by making a fusion, using 
the following charge: Ore, 2 gms.; litharge, 15 gms.; sodium 
bicarbonate, 1ogms. Fuse ina hot fire, and when the fusion is 
quiet remove the crucible from the fire, pour its contents into 
a mould, and when cool detach the lead button from the slag 
and weigh it. From the weight of the lead button calculate 
the amount of nitre necessary to add to the assay to obtain a 
lead button of the proper weight. 

Most assayers prefer the use of iron nails in the assay of 
sulphides and arsenides rather than the use of nitre. Powdered 
argols, flour or powdered charcoal are the usual reducing agents 
used. The fusion is performed in either the wind- or muffle- 
furnace, and requires from 25 to 40 minutes. When the fusion 
is quiet, the assay should be allowed to remain in the furnace 
for a few minutes at a strong heat before it is withdrawn. 
When the assay is cool, the lead button is extracted from the 
slag in the same manner as in the scorification-assay. 

The lead button should weigh from 8 to 18 grammes when 
4A. T. to1 A. T. of ore is taken, the weight depending some- 
what upon the richness of the ore. Should the lead button be 
hard (due to copper) or brittle (due to As, Sb, Te, etc.), or 
should a button of matte or speiss be formed, it should be 
scorified, with the addition of test-lead or borax, if necessary, 


128 A MANUAL OF PRACTICAL ASSAYING. 


before cupellation. The lead button is finally cupelled, the 
silver-gold button weighed, and parted as described before. 

In the case where gold only is determined by the crucible- 
assay, it is usual to add silver to the charge before fusion, either 
in the form of pure silver foil or a small crystal of silver nitrate, 
unless the ore is known to contain sufficient silver to insure 
parting. The charge should always contain an excess of 
litharge, as it serves as an excellent flux and renders the slag 
fluid. The litharge used should be thoroughly sampled and 
the silver which it contains determined. A good charge for 
this purpose is: Litharge, 2 A. T.; sodium _ bicarbonate, 
1 A. T.; argol, 1 gm. The amount of silver which 
litharge used in each assay contains should be deducted from 
the result of the assay. The crucibles should never be more 
than three-fourths filled, and in case nitre is used not over two- 
thirds. 

The assays are usually made in duplicate, and the buttons 
should agree within 0.5 oz. silver per ton on ore assaying 100 
oz. per ton. The results in gold should agree almost exactly. 
For gold assays by this method the general practice is to run 
two assays of 4 A. T. of ore each, and part the buttons together. 
In the case of rich ores the buttons are parted separately as a 
check. The table on the following page SNS the charges for 
different ores. 

In the case of copper, iron, and sreenient pyrites it is prefer- 
able to roast the ore previous to assay. After Lose ae the 
ore is treated as an oxidized ore. To roast, weigh out 4 A. T. 
of the ore, introduce into a clay roasting-dish and cues in the 
muffle, stirring from time to time. The addition of ammonium 
carbonate (commercial salt) facilitates the roasting. 

The special method (see Part III, Chapter IV) is especially 
adapted to the assay of pig copper, copper mattes, copper and 
arsenical pyrites, etc. 

Cupellation.—Cupellation is performed in a small cupel 
made of powdered and sifted bone-ash. In making up the 
cupels the addition of a small amount of potassium carbonate 
to the water used to moisten the bone-ash aids in making it 


129 


GOLD AND SILVER. 


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130 A MANUAL OF PRACTICAL ASSAYING. 


adherent. The cupel should always weigh a little more than 
the lead button to be cupelled. A very convenient size isa 
cupel weighing 18 gms. The cupels should be dried for a few 
days before using. 

The cupels are placed in the muffle and allowed to become 
hot before introducing the lead button. The cube of lead is 
dropped into the cupel and the door of the muffle closed until 
cupellation commences. As soon as cupellation begins, indi- 
cated by the surface of the lead becoming bright and fumes 
arising from the cupel, the door of the furnace is opened. The 
temperature should be controlled within rather narrow limits. 
If the temperature is too low there will be a considerable loss 
of silver and a liability of the button “freezing” (solidifying), 
when the assay is ruined, as it is not safe to accept the results 
from a frozen button. If the temperature is too high there 
will be a considerable loss of silver by oxidation and also prob- 
ably a mechanical loss in the lead fumes. The proper control 
of the temperature can be learned only by experience. A safe 
rule is to have the cupels show a slight ring of litharge crystals 
(feather litharge) around the edges. As the cupellation pro- 
ceeds the lead is oxidized, part being absorbed by the cupel 
and part passing off in fumes. Just before the last traces of 
lead are removed the button will exhibit a play of colors, 
owing to a thin film of litharge on the surface. At this point 
the temperature should be quite high in order to insure the 
removal of all the lead. This is usually accomplished by push- 
ing the cupel back in the muffle. When the lead is all re- 
moved the play of colors ceases, the button “brightens” or 
“winks” and solidifies. The cupel should be allowed to re- 
main in the furnace for a few minutes (there is no loss of silver 
after the button solidifies), when it is removed and cooled pre- 
vious to weighing. If the button of silver is large it is best to 
cover it with a hot cupel before removing from the muffle, and 
remove it gradually, otherwise the button is liable to spit or 
sprout, which may occasion loss. It is never safe to accept a 
sprouted button. 

The button, when cold, is removed from the cupel by a 


¢ 


GOLD AND SILVER. 131 


pair of nippers, squeezed slightly in the nippers, and its bottom 
brushed with a stiff bristle- or wire-brush, when it is ready for 
weighing. 

The weighing of the gold-silver button is performed ona 
_button-balance, which should weigh accurately to within o.10 
milligramme. In the case of small buttons and where +, 
A. T. is taken for assay, the balance used should be the gold 
balance, and should weigh to within 0.01 milligramme. The 
weight of the gold-silver button being noted, the button is 
ready for parting. 

Parting.—Prior to parting it is best to flatten the button by 
a few light blows, especially if it contains much gold. In order 
that the button will part it should contain at least two and one 
half times as much silver as gold. If the button does not con- 
tain sufficient silver to insure parting, pure silver in the shape 
of foil is added on acupel and fused by means of the blowpipe 
flame. After alloying, the button is flattened and is ready 
for parting. The button is placed in a small porcelain crucible 
and c. p. nitric acid of 1.16 sp. gr.is added.* The crucible and 
its contents are now warmed on an iron plate until all action 
of the acid has ceased, when the solution is brought to a boil. 
The crucible is now removed from the plate and the gold col- 
lected in one mass by gently rotating and tapping the crucible. 
The solution is then poured off and fresh acid of 1.26 sp. gr. is 
added. The contents of the crucible are now boiled for three 
minutes, the gold collected in one mass, and the acid poured off. 
The gold is now washed three times with hot water, and the 
last drops of water removed from the crucible. A convenient 
piece of apparatus for removing the last drops of water is a 
piece of glass tubing drawn to a fine point at one end. The 
water is removed by suction on the large end of the tube. The 
crucible is now warmed on the iron plate until thoroughly dry, 
when it is ignited over a lamp or in the muffle. The gold 
should be bright, and have the characteristic color of pure gold 
The gold is now ready for weighing on the gold balance. 








* Most western assayers use acid of only one strength having a sp. gr. of 
about 1.20. 


132 A MANUAL OF PRACTICAL ASSA VING, 


Some assayers prefer to part in a test-tube or small parting 
matrice. If the parting is done in a test-tube or matrice the 
tube is rinsed out twice with warm distilled water, and then 
filled with water and inverted over a small porcelain crucible. 
When the gold has all settled to the bottom of the crucible 
the tube is removed, the water poured off, and the gold dried, 
ignited, and weighed as before. 

The only exception to the above methods is in the case of 
an ore containing metallic scales. Such ores should be assayed 
by the special method described in Part III, Chapter VIII. 

On the Pacific coast the fusion for the assay of low-grade 
gold ores is usually performed in the crucible or wind-furnace, 
from 2 A. T. to 4 A. T. of ore being taken. This method pre- 
sents the advantages that large quantities of ore are taken for 
assay, and that only one fusion is necessary for each assay 


CHAPTER VIII. 
MERCURY (Hg). 


THE wet methods for the determination of mercury are 
extremely tedious, and at the same time far from accurate, 
unless extreme precautions are observed. 

The distillation methods, as described by Fresenius, Rick- 
etts, Mitchell, etc., are good, and are to be recommended 
where the percentage of mercury present is large. 

The two following methods have been tested and proved 
to be accurate, and, as they are simple and rapid, are to be 
recommended, especially when the percentage of mercury 
present is small. They both depend upon the distillation of 
the mercury and catching it on gold in the form of amalgam.* 

First Method.— Mix from 0.2 to 2.0 grammes of ore with 
from I to 4 grammes of iron filings (iron filings are preferable 
to lime, as they render the mass porous and facilitate the 
distillation) in a porcelain crucible of sufficient size, Prepare 
a cover for the crucible of sheet gold. This cover should be 
made in the form of a dish, so that it can be kept cool by 
keeping it filled with water. It should be of a diameter some- 
what larger than the diameter of the crucible, so that its sides 
project over the outer rim of the crucible. The weight of such 
a cover will be from 7 to Io grammes. 

Place the crucible in the ring-stand, fit on the cover, and fill 
it with cold water. Now heat the crucible gradually with the 


* Silver suggests itself as a substitute for gold, but as the author has never 
tried silver he cannot recommend it. 


133 


134 A MANUAL OF PRACTICAL ASSA YING. 


flame of a Bunsen burner, care being taken to keep the upper 
part of the crucible cool, and to especially keep the gold cover 
cool. The first can be accomplished by allowing the flame 
to play only around the bottom of the crucible, care being 
taken to never allow it to reach the upper sides; and the 
second by adding cold water to the cover from time to time. 
It -will require from 10 to 30 minutes to distil off all the 
mercury. When the distillation is completed remove the gold 
cover, pour off the water, dry carefully, and weigh. The in- 
crease in weight of the gold cover (it having been dried and 
weighed before the operation) represents the mercury. 

Second Method.—This method is essentially the same as 
the above, the form of apparatus used only being different. 

Prepare a piece of combustion-tubing about 14 inches long 
and closed at the left-hand end. Introduce a weighed quantity 
of the ore, which should be mixed with iron filings and lime, 
into the tube, shaking it down into the closed end. On top of 
the ore place a plug of ignited asbestos. Into the right-hand 
end of the combustion-tube introduce a spiral of gold-foil of 
which the weight has previously been determined, and a rubber 
cork connected with a small glass tube. This small tube 
should be about 18 inches in length, and should be bent up in 
the form of an Lat the open or right-hand end. It can be 
kept cool by wrapping around it a cloth saturated with cold 
water. This second small tube is to catch any mercury which 
might pass the gold-foil and not be caught by it. 

After the apparatus is connected up, heat the left-hand 
end of the tube containing the ore, to drive off the mercury, 
gradually raising the temperature, but keeping the right-hand 
end of the tube containing the gold spiral cool. Should 
any mercury condense in the combustion-tube it can be driven 
forward by moving the flame of the burner towards the right. 
After all of the mercury is distilled off, which will require from 
10 to 30 minutes’ heating, remove the heat, and allow the tube 
to cool. When cool disconnect the apparatus, examine the 
small tube, and if it contains no mercury remove the gold spiral, 
and weigh. The increase in weight of the gold will represent 


MERCURY. 


vercury. Should there be any mercury collected 
sm 1 tube, which will seldom happen if the operation was 
properly conducted, it must be collected and weighed, its 
weight being added to the weight of mercury caught by the 
gold spiral. | 
rn, P This process properly performed will give excellent results. 





CHAPTER IX. 
LEAD (Pb). 


NUMEROUS methods have been proposed for the determina- 
tion of lead, both volumetrically and gravimetrically, but the 
following are the only ones which are extensively used: 

I. Fire-assay ; 

2, Gravimetric determination as lead sulphate, and weigh- 
ing as such ; 

3. Volumetric determination with a standard solution of 
potassium ferrocyanide ; 

4. Volumetric determination with a standard solution of 
potassium permanganate ; 

5. Volumetric determination with a standard solution of 
ammonium molybdate. 

The first method is generally used in the United States and 
elsewhere for the determination of lead in purchasing ores. 
Its advantages are: Rapidity, ease of execution, and the large 
number of assays which may be made in a given time. Its 
disadvantages are: All the lead is seldom reduced, and the 
buttons are seldom pure. If the ore contains Sb, Sn, Bi, Cu, 
Fe, and Zn, the button is liable to contain more or less of these 
impurities. A recent analysis of the buttons resulting from 
several hundred lead determinations at one of our large smelt- 
ing works showed the buttons to only contain 96 per cent 
lead, as an average. The method, and with good reason, is 
gradually giving way to the more accurate volumetric methods. 
Some chemists now use the volumetric methods on mattes 
and all but pure ores. 

The advantages of the second method are that the results 
obtained are extremely accurate. Its disadvantages are: Time 
and nicety of manipulation required. 

136 


LEAD. 137 


The advantages of the third, fourth and fifth methods are 
rapidity and ease of execution. The disadvantage of the fourth 
method is that the results are apt to be a trifle low on account 
of the incomplete precipitation of the lead as oxalate, but for 
technical purposes it leaves but little to be desired. The fifth 
method answers all requirements for technical purposes and is 
at present extensively used in the West. As this method fails 
where much lime is present, owing to the precipitation of calcium 
molybdate, in such cases it will have to be slightly modified. 
A good method to follow where lime is present is to proceed 
according to Knight’s method up to the point of precipitation 
of the lead on zinc. Dissolve the precipitated lead in dilute 
nitric acid, using as small a quantity as possible, render the solu- 
tion alkaline with ammonia, neutralize with acetic acid, and 
proceed with the titration as usual. 

I. Fire-assay.—The general practice in Colorado is as fol- 
lows: 5 grammes of pulverized ore are mixed with from 15 to 
20 grammes of lead flux in a clay crucible, a cover of borax is 
added, and the fusion made in a muffle-furnace. The time of 
fusion with a good fire is from 15 to 20 minutes. In the case 
of sulphide or base ores one or two iron nails or a few loops 
of iron wire are added to the charge. When the fusion has 
become quiet the crucible is allowed to remain in the muffle 
from I to 5 minutes, when it is drawn out and its contents 
poured into a scorifier-mould. As soon ascold the button and 
slag are removed from the mould, and the button extracted 
from the slag by pounding with a hammer. The button is 
pounded out thin on the anvil, and should be soft and malle- 
able. If brittle it contains Sb, S, etc. If hard it probably 
contains Fe, Cu, etc. The slag should be vitreous and brittle, 
and should not contain shots or globules of lead. Duplicate 
assays should agree to within about 0.5 per cent. 

2. Gravimetric Method, weighing as PbSO,.—\Lead 
may be determined in its ores and furnace-products by treating 
1.0 gramme of ore with 7 to Io cc. of strong nitric acid in a 
flask or beaker of about 250 ce. capacity, covered with a watch- 
elass, and heating until the violent action ceases and the sul. 


138 A MANUAL OF PRACTICAL ASSAYING. 


phur is oxidized. Then add to cc. of dilute sulphuric acid (5a 
per cent strong sulphuric acid and 50 per cent water), and boil 
until the nitric acid is expelled and dense white fumes of sul- 
phuric anhydride appear. ‘Then cool, dilute cautiously with 
about 50 cc. of water, and shake in the flask to break up any 
clots which may have formed, and also to cause the basic sul- 
phate of iron to go into solution. If very much iron is present, 
as in the case of mattes, it may be necessary to heat the 
solution in order to dissolve the basic sulphate of iron. Then 
cool, filter, and wash the residue, containing lead sulphate and 
gangue, with water containing I per cent of sulphuric acid, and 
then with about 4o cc. of alcohol. Dissolve the lead sulphate 
on the filter, also what may stick to the sides of the flask, with 
a slightly acid solution of ammonium acetate, made by adding 
acetic acid to strong ammonia until the solution is slightly 
acid, then bringing back to an alkaline state with dilute am- 
monia, and then back to an acid state with a few drops of 
acetic acid. The solution should be warm when used. From 
two to three washings with ammonium acetate will be neces- 
sary to dissolve all of the lead sulphate. After washing with 
the acetate solution, wash with warm water. The lead will 
now all be in solution in the filtrate, whilst the silica, calcium 
sulphate, etc., will remain behind on the filter. Acidify the 
filtrate with an excess of sulphuric acid, cool, and filter off the 
sulphate of lead, washing as before with a I per cent solution 
of sulphuric-acid water and afterwards with alcohol in order 
to displace the sulphuric acid. The filtrate may be tested for 
lead by adding a few drops of hydrochloric acid and passing a 
current of sulphuretted hydrogen gas through it. Should any 
lead sulphide be precipitated, it should be filtered off and dis- 
solved in a small quantity of nitric acid. Sulphuric acid 
should then be added, and the nitric acid be driven off by 
boiling. The lead sulphate thus recovered from the filtrate 
should be added to the other precipitate. The filter and its 
contents are then dried at a moderate temperature (not above 
100° C.), and when dry transfer the contents of the filter-paper 
as completely as possible to a clean watch-glass by inverting it 


LEAD. 139 


ever the glass and working it with the fingers. Then burn the 
filter in a weighed porcelain crucible, and after it is burned and 
ignited add to the ash a few drops of nitric acid (to dissolve 
the lead reduced to metallic lead by the carbon of the filter- 
paper) and warm, then add two or three drops of sulphuric 
acid, evaporate off the excess of acid, brush the precipitate 
into the crucible from the watch-glass, and ignite all. Cool, 
and weigh the crucible and its contents. This weight, less the 
known weight of the crucible and filter-ash, will be the weight 
of the lead sulphate. To calculate the weight of the lead, 
multiply the weight of the lead sulphate by 0.68317. 

3. Volumetrically, by Means of Standard K,FeC,N,. 
—This method, while not new,* has lately come into promi- 
nence,t and is highly recommended. Treat 0.5 to I gm. of ore 
in the same manner as with Alexander’s method, and filter off 
and wash the precipitated lead sulphate. Wash this precipitate 
back into the flask or beaker with a minimum amount of water, 
and add 30 cc. of a saturated solution of ammonium carbonate. 
Heat quickly to boiling, and boil at least one minute in order 
to decompose any calcium sulphate which may have formed. 
It is essential that any calcium sulphate present should be 
converted into a carbonate, as otherwise the sulphate would 
react upon the dissolved lead and thus cause low results. 
Filter and wash thoroughly with hot water containing a little 
ammonium carbonate. Dissolve the washed carbonate of lead 
in strong c. p. acetic acid, dilute to about 180 cc., and titrate 
with the standard ferrocyanide solution in the same manner 
as described for zinc(p. 207). The ferrocyanide solution should 
be of such a strength that each cc. will precipitate o.o1 gm. of 
lead. It is prepared by dissolving 14 gms. of. c. p. potassium 
ferrocyanide in one litre of water. 

4. Volumetrically, by Means of Standard KMnO,.—For 
ores and furnace-products the method of procedure is as fol- 
lows: Treat from 0.5 to I.o gramme of the material, according 
to its richness, with from 8 cc. to 15 cc. of strong nitric and 


* Eng. and Min. Jour., Vol. XLIX, p. 178, Feb. 8,1890. Mining Industry, 
Vol. VI, No. 16, Apl. 1890. 
+ Jour. Am. Chem. Society, Oct. 1893. 


I40 A MANUAL OF PRACTICAL ASSAYING. 


from 8 tc. to 15 cc. of strong sulphuric acids in a casserole, 
cover with a watch-glass, and heat until decomposition is 
effected and fumes of sulphuric anhydride appear. Remove 
the casserole from the heat and cool; when cool, gradually 
add about 50 cc. of cold water, heat to boiling, and immediately 
filter. Wash well with boiling water acidified with sulphuric 
acid, and finally with plain hot water. Rinse the insoluble 
residue into a beaker of about 200 cc. capacity, using not more 
than 50 cc. of water; add 5 cc. of concentrated hydrochloric 
acid, cover with a watch-glass, and boil for 5 minutes. The 
sulphates of lead and lime pass into solution. 

If much silica and barium sulphate is present, it is best to 
filter and wash well with boiling water. The filtration must 
be done rapidly. Small quantities of silica do not interfere, 
but larger quantities prevent the subsequent precipitation of 
the lead in one spongy mass. 

Dilute the solution with water to about 100 cc., keeping it 
hot but not boiling. Add two grammes of granulated zinc 
(free from lead) to the solution, when the lead will immediately 
begin to be precipitated as a metallic sponge. When the 
action of the acid on the zinc has apparently ceased add 0.5 
gramme more of zinc and allow to stand for 5 minutes. Now 
boil the solution, and add Io cc. of concentrated hydrochloric 
acid. This dissolves the remainder of the zinc very quickly, 
and when the reaction is completed the lead sponge will be 
found floating on the surface of the liquid. Decant the solu- 
tion, wash the lead sponge with cold water, and press it out 
flat with the finger. Dissolve it in 1 cc. of concentrated nitric 
acid and 20 cc. of hot water. Add a slight excess of sodium 
carbonate (salt), and redissolve the precipitated lead carbonate 
by the addition of 5 cc. of strong acetic acid. Add 20 cc. of 
95 per cent alcohol, heat the solution to 65° C., and precipitate 
the lead with a saturated solution of pure crystallized oxalic 
acid. The lead comes down immediately as a dense white 
crystalline precipitate. Stir briskly until the precipitate settles, 
leaving a perfectly clear supernatant liquid. Filter and wash 
the precipitate three times with a hot mixture of alcohol and 


en) 


LEAD. I4! 


water (1 alcohol, 1 water), and then four times with hot water 
alone. In washing the precipitate it is well to use a fine jet, 
keeping the stream on the filter and not allowing it to flow on 
the glass, as otherwise the precipitate is liable to creepap on 
the funnel and thus occasion loss. When thoroughly washed, 
the precipitate is rinsed into a flask or beaker with about 50 
cc. of hot water, add 5 cc. of concentrated sulphuric acid and 
determine the oxalic acid which was combined with the lead 
in the same manner as in the estimation of lime volumetrically, 
using a standard solution of potassium permanganate. (See 
Part I, Chap. XXIII.) 

A quite dilute solution of permanganate should be used— 
not stronger than 1.58 grammes of K MnO, to 1000 cc. of water. 
One cc. of such a solution will be equal to about 0.05 gm. of 
lead. The standard of the solution in terms of lead is obtained 
by multiplying the standard in terms of oxalic acid by 1.6428. 

Bismuth and antimony are the only impurities of the ores 
which are liable to affect the results. By adding a large excess 
of sulphuric acid to the nitric-acid solution, so that when the 
evaporation takes place and the sulphuric-acid fumes appear 
the mass will be in a fluid and not a pasty condition, and 
allowing the mixture to cool and adding cold water gradually 
to avoid heating, all of the bismuth goes into solution, and 
remains in solution for a sufficient length of time to allow 
filtration and a separation of the sulphate of lead to be 
effected. If sufficient sulphuric acid is used, most of the anti- 
mony will likewise be held in solution. Should some antimony 
remain with the lead sulphate, it will be reduced to the metal- 
lic state by the zinc, and when the solution of the lead is 
effected with the nitric acid it will remain behind as the in- 
soluble oxide, and thus be eliminated. 

A determination may be effected in from 35 to 40 minutes. 

This method is due to F. C. Knight.* 

According to Mr. Knight’s results, about 99.6 per cent of 
the lead present is obtained. 

A. H. Lowt proposes a modification of Knight’s method 
which presents some advantages. 





* Proceedings of the Colorado Scientific Society, Nov. 7, 1892. 
+ Journal of the Am. Chem. Society, Oct. 1893. 


142 A MANUAL OF PRACTICAL ASSAYING. 


5. Volumetrically by Means of a Standard Solution of 
Ammonium Molybdate.—This method is based upon the 
fact that ammonium molybdate when added to a hot solution 
of lead acetate will produce a precipitate of lead molybdate 
(PbMoO,) which is insoluble in acetic acid. Any excess of 
ammonium molybdate will give a yellow color with a freshly 
prepared solution of tannin. The solution of tannin is made 
by dissolving one gramme of tannin in 300 cc. of water, and is 
used as an indicator on a porcelain plate. The standard solu- 
tion of ammonium molybdate is prepared by dissolving 9 
grammes of the salt in 1000 cc. of water. This should give a 
solution of which 1 cc. is equal to about 0.01 gm. of lead. If 
the solution is not clear, it can be clarified by adding a few 
drops of ammonium hydrate. 

To standardize the molybdate solution weigh out 0.3 gm. 
of pure lead sulphate and dissolve it in hot ammonium acetate; 
acidify the solution with acetic acid and dilute with hot water 
to 250 cc. Heat to boiling, and add from a burette the molyb- 
date solution until all the lead is precipitated as a white pre- 
cipitate. This is ascertained by placing the drops of tannin 
solution on a porcelain plate and adding drops of the solution 
in the beaker to the tannin drops from time to time. As long 
as the lead is in excess no color is produced, but as soon as the 
molybdate is in excess a yellow color is produced (0.3 gm. 
PbSO, X 0.68317 = 0.20495 gm. Pb). This operation should 
be repeated, and from the number of cc. of the molybdate 
solution used in each case the value of one cc. is calculated in 
the usual way. 

To determine the lead in an ore- er furnace-product by this 
method 0.5 or 1.0 gm. of substance is weighed out (according to 
the percentage of lead: if 30 per cent or over, 0.5 gm. will be 
sufficient) and decomposed in a casserole by heating with 15 
cc. of strong nitric and 10 cc. of strong sulphuric acids. When 
the nitric acid is completely expelled, which is indicated by 
fumes of sulphuric anhydride, the casserole is removed from 
the heat and its contents cooled. Dilute with cold water, stir 
thoroughly, and boil until all soluble sulphates are dissolved. 


LEAD. 143 


Now filter, leaving as much of the precipitate in the casserole 
as possible, and wash twice with hot dilute sulphuric acid and 
once with cold water. Now add to the sulphate of lead re- 
maining in the casserole hot ammonium acetate, pour the hot 
solution on the filter, and allow it to run through into a clean 
beaker. This operation is repeated until the sulphate of lead 
is completely dissolved. Now wash out the casserole thoroughly 
with hot water into the filter. Acidify the solution in the 
beaker with acetic acid, dilute up to 250 cc. with hot water, 
and heat to boiling. Runin from the burette the standardized 
solution of ammonium molybdate until all the lead is precipi- 
tated, stirring thoroughly after each addition of the molybdate, 
and testing a drop of the solution from time to time on the 
porcelain plate with the tannin solution. From the number of 
cc. of the molybdate solution used calculate the per cent of 
lead. 

Arsenic, antimony, and phosphorus do not interfere with 
the method as they pass through the filter into solution. 

A determination can readily be made in thirty minutes. 

The method is largely used in Colorado for the determina- 
tion of lead in ores containing copper, and in both lead and 
copper mattes. The results are excellent.* 

This method is due to H. H. Alexander. ft 


* State School of Mines Scientific Quarterly, Vol. I, No. 4. ! 
t+ The Engineering and Mining Journal, Vol. LV, No. 13, April 1, 1893. 


CHAU TUN. 
ARSENIC (As). 


FoR the technical estimation of arsenic in ores and metal- 
lurgical products, the following method, which was devised and 
published by Dr. Richard Pearce, of Denver, Colo.,* is the 
most rapid and at the same time one of the most acCurass 
methods which we have: 

The finely powdered substance for analysis is mixed in a 
platinum crucible with from six to ten times its weight of 
a mixture of equal parts of sodium carbonate and potassium 
nitrate. The mass is then heated with gradually increasing 
temperature to fusion and allowed to remain for a few minutes 
in that state. It is then allowed to cool, and the mass removed 
by the addition of warm water. It is best to remove the mass 
by warm water, pouring in to acasserole, and, after the whole is 
transferred to the casserole, to heat to a boiling temperature and 
filter. The arsenic isia the filtrate as an alkaline arseniate, which 
is then acidified with nitric acid and boiled to expel carbonic 
acid and nitrous fumes. It is then cooled and almost exactly 
neutralized as follows: Place a small piece of litmus-paper in 
the liquid, which should show an acid reaction, and then grad- 
ually add ammonia until the litmus-paper turns blue, avoiding 
a great excess. Again make slightly acid with a drop or two 
of concentrated nitric acid, and then, by means of very dilute 
ammonia and nitric acid, added drop by drop, bring the solu- 
tion to a condition that the litmus-paper, after having previ- 
ously been reddened, will in the course of half a minute begin 
to turn blue. If the neutralization has caused much of a pre- 


* Proceedings of the Colorado Scientific Society, Vol. I. 
144 


‘ a rea 9.) % 
wt i ike *y } 
ew q 


ARSENIC. 145 


cipitate (alumina, etc.) the solution is best filtered at once in 
order to render the subsequent washing and filtration of the 
arseniate of silver more rapid. If this filtration is unnecessary, 
the litmus-paper is drawn up the sides of the beaker, leaving 
a portion, however, yet immersed in the liquid. A neutral 
solution of nitrate of silver is now added in slight excess, and 
after stirring the color of the immersed portion of the litmus- 
paper is noted, and if necessary the neutralization is repeated. 
The second neutralization is always necessary when the 
amount of arsenic present is large, as nitric acid is set free in 
the reaction between the alkaline arseniate and silver nitrate, 
according to one or both of the following equations, or those 
of the corresponding potassium salts: 


3AgNO, + NaH,AsO, = Ag,AsO, + NaNO, + 2HNO,, 
and 


3AgNO, + Na,HAsO, = Ag,AsO,-+ 2NaNO, + HNO,,. 


The precipitated arseniate of silver, which is of a brick-red 
color, is finally collected on a filter and well washed with cold 
water. Asa further precaution, the filtrate may be tested with 
silver nitrate, dilute nitric acid, and ammonia to see if the pre- 
cipitation is complete. The object is now to determine the 
amount of silver in the precipitate of arseniate of silver, and 

from this to calculate the arsenic. This may be accomplished 
in two ways: First, the precipitate may be dried in a scorifier, 
test-lead and borax added, and a scorification-assay made to 
determine the amountof silver. If this method is adopted any 
soluble chloride must be removed earlier in the process. Gen- 
_ erally but few ores will be encountered in ‘which any soluble 
chloride is present. Another and shorter method of determin- 
ing the silver is as follows: Dissolve the arseniate of silver on 
the filter with dilute nitric acid (which leaves undissolved any 
silver chloride) and titrate the filtrate, after addition of about 
5 cubic centimetres of a saturated solution of ferric ammonium 
sulphate, with a standard solution of ammonium sulphocyanate 
(about 5 grammes of the salt to the litre of water), run in until 





146 A MANUAL OF PRACTICAL ASSAYING. 


a faint-red tinge is obtained, which remains after considerable 
shaking. The shaking breaks up any clots of sulphocyanate of 
silver, and frees any solution held mechanically. 

From the formula 3Ag,O, As,O, we find that 648 parts of 
silver represent 150 parts of arsenic, or 108 parts of silver 25 
parts of arsenic. 

In determining arsenic in ores very rich in arsenic, such as 
arsenopyrite, niccolite, etc., it is desirable to add a few drops 
of fuming nitric acid to the weighed sample in the platinum 
crucible prior to the usual fusion. This oxidizes the arsenic 
and sulphur present, and prevents subsequent loss by defla- 
gration; this precaution should also be adopted in the deter- 
mination of arsenic in sulphide of arsenic obtained in the 
ordinary course of analysis. Molybdic and phosphoric acids, 
which behave similarly to arsenic under this treatment, inter- 
fere, of course, with the method. Antimony, by forming 
antimoniate of sodium, or potassium, remains practically in- 
soluble and without effect. A determination can be made in 
30 minutes by this process. A modification of the above 
method has been proposed by R. C. Canby,* in which he 
neutralizes the solution with an emulsion of c. p. zinc oxide. 
The zinc oxide is added in slight excess (see Chapter XX: 
manganese), no delicate testing with litmus-paper and alter- 
nate adding of dilute ammonia and nitric acid becomes neces- 
sary, thus saving time. The slight excess of zinc oxide also 
tends to render the subsequent filtration and washing of the 
arseniate of silver more rapid, as it holds the gelatinous silica 
which is precipitated on neutralization. The writer has tried 
this method of neutralization, and regards it as an improve- 
ment on the method as originally given. 


* Transactions of the American Institute of Mining Engineers, Vol. XVII 
P. 77- 


CHATI ER XI. 


ANTIMONY (Sb). 


ANTIMONY in ores, mattes, etc., is best determined by one 
of the following gravimetric methods. The first method is the 
most accurate, and is to be recommended in scientific work and 
where great accuracy is required. The second method is more 
rapid and simpler than the first. and answers all purposes for 
technical work. 

First Method.—Precipitation of the antimony as sulphide, 
conversion of the sulphide into antimony tetroxide (Sb,O,), 
and weighing as such. Method due to Bunsen.* 

Second Method.—Precipitation of the antimony as metal- 
lic antimony, and weighing as such. This method is due to 
Carnot.t+ 

First Method.—T reat 1.0 gm. of finely pulverized ore in a 
flask, similar to the flask used in the determination of copper, 
with 5 cc. of concentrated nitric acid, 10 cc. of concentrated 
hydrochloric acid, and 3 gms. of crystallized tartaric acid. 
Heat until the substance is nearly dry, in order to expel most 
of the free acid. To the nearly dry mass add 100 cc. of water, - 
make alkaline with ammonia, add 10 cc. of yellow ammonium 
sulphide, and warm gently for one hour. Sufficient ammonium 
sulphide should be added to render the fluid yellow. Filter, 
and wash with hot water until the filtrate runs through color- 
less. The antimony will be in the filtrate as ammonium sulph- 
antimonate. Acidify the filtrate with hydrochloric acid and 
allow the precipitate to settle. Should the ore be not 
thoroughly decomposed by the above treatment with acids, dry 





* Fresenius, Quant. Anal., § 125, p. 243. 
+ Comptes Rendus, CXIV. p. 587. 
147 


¥48 A MANUAL OF PRACTICAL ASSAYING. 


the residue remaining on the filter, and fuse it with 5 gms. of 
sodium carbonate and 1.0 gm. of sodium nitrate. Treat the 
fused mass with an excess of hydrochloric acid and 1.0 gm. of 
tartaric acid, evaporate off the excess of acid, add 25 cc. of 
water, render alkaline with ammonia, and treat with yellow 
ammonium sulphide. Filter, wash, and acidulate the filtrate 
with hydrochloric acid. Allow the precipitated antimony sul- 
phide to settle, and filter off the precipitate on the same filter 
as before washing with hot water. Wash finally with alcohol 
to displace the water adhering to the precipitate, dry it at a 
low heat, wash with carbon disulphide to dissolve the free 
sulphur, and dry at a temperature of not over 100° C. As 
soon as the precipitate is dry enough to remove it from the 
filter, brush it into a watch-glass, cleaning the paper as 
thoroughly as possible, and place the filter in a large covered 
porcelain crucible which has been previously weighed. Moisten 
it with concentrated nitric acid, add 4 to 5 cc. of red fuming 
nitric acid, and evaporate on a water-bath to dryness. Now 
transfer the precipitate to the crucible and add a little concen- 
trated nitric acid by means of a pipette, inserting the point of 
the pipette under the edge of the lid. When the violent action 
has ceased add 10 times the volume of the precipitate of red 
fuming nitric acid, and evaporate to dryness on the water-bath, 
removing the cover as soon as all danger of loss by spirting is 
past. Finally ignite cautiously over a Bunsen burner to expel 
the sulphuric acid and convert the antimony into tetroxide. 
Weigh the tetroxide and calculate the antimony. The weight 
of the precipitate multiplied by 0.78947 equals the weight of 
antimony. 

In very accurate work all the filtrates should be treated with 
sulphuretted hydrogen to recover any traces of antimony which 
may have possibly escaped. 

A determination requires from three to four hours, 

Second Method.—This method consists essentially in obtain- 
ing the antimony in a hydrochloric-acid solution, in precipitat- 
ing it with tin and weighing it in the metallic state. The 
method varies somewhat, according to whether the ores are 


ANTIMONY. 149 


oxidized or sulphide ores, and according to whether they con- 
tain lead or not. 

Sulphides.—Take from 2 to 5 gms. of ore, according to its 
supposed percentage of antimony, so that we may operate on 
about 1.0 gm. of antimony. Treat in a small flask, as before, 
with 50 to 60 cc. of concentrated hydrochloric acid, and heat 
on a sand-bath. When the acid appears to have no further 
action and the ore is decomposed, decant the clear liquid 
through a filter and add a fresh quantity of acid. Heat again, 
and continue until the sulphides are thoroughly decomposed. 
Decant through the filter and renew the acid once more, adding 
I or 2 drops of nitric acid to complete the attack; heat at 
100° C., filter, and wash the insoluble gangue with hydrochloric 
acid diluted with water. 

The combined filtrates are diluted with an equal volume of 
water, a blade of tin is introduced and the solution heated to 
80° or go’ C. The precipitation begins immediately, and for 
1.0 gm. of antimony is completed in about 90 minutes. 

The precipitate is washed by decantation, replacing the 
liquid with dilute hydrochloric acid to remove salts of tin and 
any other salts which may be present. The metallic antimony 
is brought upon a weighed filter, washed thoroughly with hot 
water, and finally with alcohol. The metallic antimony is then 
dried at 100° C. and weighed together with the filter. 

If the operation is conducted as above there is neither 
appreciable loss nor oxidation. 

Oxidized Ores.—The oxides of antimony are frequently 
attacked with extreme difficulty by hydrochloric acid. We are 
then exposed either to notable losses by volatilization or to an 
incomplete solution of the antimony. 

The method of procedure is as follows: The ore is placed 
in a small flat-bottomed flask, in which the quantity of from 2 
to 5 gms. forms a light layer permeable to gases. Place an 
elbow-tube in the flask, by means of a cork in the neck, sc 
that its lower end descends almost to the level of the ore. 
Through the tube passa current of dry sulphuretted hydro. 
gen, placing the flask upon a piece of wire-gauze at the height 


150 A MANUAL OF PRACTICAL ASSAYING. 


of a few inches above the flame of a Bunsen burner, so that 
the temperature shall not exceed 300° C., producing no vola- 
tilization of the antimony sulphide. The ore remains pulveru- 
lent and is permeated by the hydrogen sulphide, which acts at 
the same time as a reducing and sulphurizing agent. The 
surface of the ore is renewed from time to time by shaking 
the flask. The conversion is complete in about one hour. 
When cold the ore is treated with hydrochloric acid in the same 
flask. The precipitation and weighing are then effected as 
described above. Experience shows that the quantity of anti- 
mony remaining undissolved is quite insignificant. 

Ores containing Iron or Lead.—Neither the presence of 
iron nor of zinc, even in considerable quantities, interferes with 
the method. 

Lead, if present, will be precipitated with the antimony by 
the tin. Its presence can easily be detected. If present weigh 
the combined precipitates of antimony and lead, and after 
weighing heat to 50° or 60° C. in a solution of yellow sodium 
sulphide (prepared by boiling the monosulphide with flowers of 
sulphur). The antimony is rapidly dissolved, the lead being 
converted into a sulphide which is insoluble. 

Filter off the lead sulphide, wash thoroughly, and dry. 
Finally ignite the precipitate in a Rose crucible in a stream of 
sulphuretted hydrogen, and weigh. Eighty-five per cent of 
the weight of this lead sulphide represents the corresponding 
weight of the metallic lead, which is to be deducted from the 
combined weight of the antimony and lead. 


CHAPTER XII. 
TIN (Sn). 


A GREAT many methods have been proposed for the separa- 
tion and estimation of tin, for which see Fresenius, Rose, 
Cairns, Crooks, etc. It is the opinion of the author that the 
following methods are the best in use: 

First Method.—Fuse 1.0 gm. of very finely pulverized rich 
ore with 3 gms. of sulphur and 3 gms. of dry sodium carbonate 
in a large porcelain crucible over a Bunsen burner for about 
one hour. The ore and flux should be thoroughly mixed. The 
heat should not be too great, nor should the fusion be too 
greatly prolonged, as the sulphide of tin may become oxidized, 
and consequently be insoluble when the fusion is treated with 
water. The fusion results in the production of sodium and tin 
sulphides. If the fusion has been properly conducted the tin 
sulphide should go into solution, upon addition of water, as 
sodium sulpho-stannate. 

Allow the fusion to cool, place the crucible in a casserole, 
add hot water, and digest on the water-bath until the mass is 
disintegrated and removed from the crucible. Filter, wash 
thoroughly with hot water, and acidulate the filtrate with sul- 
phuric acid to precipitate the tin sulphide. Allow the sulphide 
to settle, keeping the solution warm; pour the clear solution on 
a filter, wash four or five times by decantation, and finally on 
the filter, using hot water. Should the precipitate run through 
the filter wash with ammonium acetate. Place the filter and its 
contents in a weighed porcelain crucible, and apply a very gentle 
heat, with free access of air until the odor of sulphurous acid is 
no longer perceptible. Gradually increase the heat to a high 

151 


152 A MANUAL OF PRACTICAL ASSA YING, 


degree, and finally add ammonium carbonate to insure the com- 
plete elimination of the sulphuric acid. The treatment with 
ammonium carbonate should be repeated several times. <A 
high heat at the beginning is to be avoided, as fumes of stannic 
sulphide are liable to escape if the heat is too high. 

The residue from the first fusion and solution invariably 
contains tin; hence it must be refused. Before fusion, if much 
iron is present it should be removed with a little dilute hydro- 
chloric acid. If but little iron sulphide is present the treat- 
ment with acid can be dispensed with. The residue is now 
dried, burned, mixed with sodium carbonate and sulphur, and 
fused as before. The fused mass is dissolved in water, filtered, 
and the tin precipitated as before. The weight of tin recov- 
ered from this second fusion is to be added to the weight 
obtained from the first fusion. If thé fusions were properly 
conducted a third fusion will generally be unnecessary.* 

After weighing the stannic oxide, it should be examined 
for silica as follows: Fuse a weighed portion with three or four 
parts of a mixture of equal parts of sodium and potassium car- 
bonates, treat the fused mass with hot water, filter, and wash. 
Acidulate the filtrate with hydrochloric acid, and should any 
silica separate out, filter it off, reserving the filter and its con- 
tents. Acidulate the filtrate with hydrochloric acid and pass 
sulphuretted hydrogen, to precipitate the tin. Filter out the 
precipitated sulphide and treat the filtrate as usual for silica, 
finally filtering through the reserved filter. Calculate the silica 
thus found to the whole weight of stannic oxide, and, after 
deducting this weight from the weight of the stannic oxide 
and silica, calculate the metallic tin. This method is due to 
Rose.t 

Second Method.—Of all the different methods proposed 
for the dry or fire assay of tin ores it is believed that the fol- 
lowing is the best. This is the German method, and is essen- 
tially as follows:{ Mix 5 grammes of ore with I.o gramme of 


— 





* School of Mines Quarterly, Vol. XIII, No. 4, p. 370. 
+ Quantitative Analysis, p. 393. 
¢ Miller, School of Mines Quarterly, Vol. XIII, No. 4, p. 372. 


eS —.’-- 


TIN. 153 


finely ground charcoal, and place in the bottom of an ordinary 
Hessian or clay crucible. Over this place 15 grammes of black- 
flux substitute mixed with I gramme of borax-glass. The 
black-flux substitute is made by mixing ten parts of sodium 
bicarbonate with three parts of flour. On top of the charge is 
placed a cover of salt, and on this several lumps of charcoal. 
The fusion is performed in the wind-furnace, using a coke fire, 
or in the muffle-furnace. The crucibles should be left in the 
fire for from one hour to one hour and twenty minutes. The 
fire should be hot—between a bright red and a white heat, but 
not as hot as a white heat. The crucibles are removed from 
the furnace and allowed to cool. When cold they are broken 
open and the slag removed from the buttons, which are then 
ready for weighing. The slag should be clear and well fused. 

This method requires that the ore should be quite pure, 
and should contain a high per cent of tin. If the ore is low- 
grade, it should be first concentrated by washing in a gold- 
pan cr by coarse jigging. In this case the sample should 
be weighed, then washed until most of the silica, iron, etc., 


.is removed. The concentrates are now dried and weighed. 


From the dry concentrates two portions of 5 grammes each 
are taken for assay. 

The method of calculating results is illustrated by the 
following example: 





Bele WEICTICd . 6 ow. ae eee sc sel py eYarecsretaleratels 500 grammes. 
Me atc a WW CISNCO 2 6. ee secs ve ie cee ees 55 ve 
Assay of 5 grammes concentrates gave tin..... Ey 
66 (73 5 (73 6é 66 Shee ae aA 66 
Re PM cfars si ciul> Seles cee «6 ele 9.054 6 vinis 3.45 
Hence we = 37.95 gms. tin in the 55 gms. of concem 
trates; and OE eee 7.59 per cent tin in the ore. 


500 


CHAPTER XIII. 


COPPER (Cu). 


Two wet methods for the determination of copper in ores 
and furnace-products are generally used in the United States, 
as follows: The volumetric assay, by a standard solution of 
potassium cyanide, and the battery-assay. In addition to 
these, the colorimetric method and the volumetric iodide 
method are sometimes used. 

Volumetric Assay by Means of Standard Potassium- 
cyanide Solution.—The best and most rapid method for 
making this assay is the method developed by Mr. A. H. 
Low, late chemist to the Boston and Colorado Smelting Com- 
pany at Argo, Colorado.* The method is essentially that of 
Dr. Steinbeck, but so modified as to save considerable time, 
while insuring equal if not greater accuracy. Treat I gramme 
of the pulverized ore in a flat-bottomed flask (250 cc. capacity), 
or casserole, with 7 cc. of nitric and 5 cc. sulphuric acid. 
Commercial acids will answer all purposes. Heat till the nitric 
acid is all expelled and the sulphuric acid is boiling freely. 
Sulphur, if present, is usually partially, sometimes entirely, 
volatilized, a portion recondensing on the neck of the flask. 
What is in the bottom of the flask should be melted into glob- 
ules, which are yellow when cold and free from copper. Allow 
the flask and contents to cool sufficiently, and add 6 grammes 
of commercial sheet zinct cut into small strips of about 3 
grammes each. Shake the contents of the flask in order to 
break up any cake formed in the bottom, and allow to stand 

+ Aluminum may be substituted for zinc with advantage. 
154 


COPPER. 155 


five minutes. Then add 50 cc. of water and 20 cc. of sulphuric 
acid to rapidly dissolve the excess of zinc, which usually takes 
about five minutes more. When solution of the zinc is com- 
plete, fill up to the neck with water, allow to settle, and decant 
the clear supernatant liquid. This may be tested for copper, 
if desired, with sulphuretted-hydrogen water, bearing in mind 
that antimony, bismuth, etc., may be present and give dis- 
colorations likely to be mistaken for copper. As a rule, no 
discoloration or only an extremely faint one will be observed, 
and consequently the test is usually omitted. Fill up with 
water and decant twice more. The residue in the flask may 
consist of gangue and copper, besides various other constitu- 
ents of the ore and the impure reagents used, such as silver, 
gold, lead, arsenic, antimony, etc., of which only silver is likely 
to interfere with the assay. Now add 5 cc., pretty exactly 
measured, of pure concentrated nitric acid, and boil, to expel 
the red fumes. Now add a single drop of strong hydrochloric 
acid, and if much silver (1 per cent or more) is thus indicated, 
add a second drop of hydrochloric acid, which is usually quite 
sufficient, and, after dilution with a little water, filter. <A 
simple cloudiness or very slight precipitate of silver may be 
disregarded. To the somewhat dilute acid solution add Io cc. 
of strong ammonia-water and cool. 

One of two courses is now to be chosen. If the color of 
the solution indicates that not more than 3 per cent of copper 
is present, add about 125 cc. of water and filter, using a filter 
of about 6 inches in diameter and folded into corrugations. It 
filters rapidly, and the small amount of dilute solution remain- 
ing in the pores of the filter generally need not be washed out. 
If a larger amount of copper is present, the 125 cc. of water is 
added and the titration with potassium cyanide is proceeded 
with, until all but about 2 or 3 per cent of the copper has been 
neutralized, and then the liquid should be filtered as before. 
The object of this filtration is to remove the gangue, lead, 
ferric hydrate, etc., which may be present, and afford a clear 
solution with which to complete the titration. The cyanide 
solution is run into the filtered liquid, and when within a few 


156 A MANUAL OF PRACTICAL ASSAYING. 


cubic centimetres of the end the bulk of the solution should 
be noted and distilled water added, if necessary, so that the 
final bulk will be about 180 cc. This is about the bulk which 
should be attained, without any dilution, in the assay of a sub- 
stance containing about 80 per cent copper, which is the maxi- 
mum amount considered in the present scheme, starting with 
one gramme of substance. The final addition of the cyanide 
should be made drop by drop, the flask being well shaken each 
time, until the blue or lilac tint can scarcely be discerned at the 
upper edges of the liquid when viewed against a white back- 
ground. Many chemists titrate to a faint rose or pink tint. 
The cyanide solution should be of such a strength that I cc. 
will correspond to 5 milligrammes of copper. Accordingly, it 
will contain from 55 to 60 grammes of commercial cyanide of 
potassium to the litre. It should be kept in a closed bottle, 
preferably of dark-green glass, covered with black paper, and 
be protected with a layer of coal-oil. To standardize, dissolve 
from three to five tenths of a gramme of pure copper-foil in 5 
cc. of pure concentrated nitric acid; boil off red fumes, dilute 
slightly, add 10 cc. of strong ammonia-water, cool, and titrate. 
When near the end add distilled water, to bring the final bulk 
up to about 180 cc., and finish as described above. 

Although most ores yield to the above treatment with 
nitric and sulphuric acid, the addition of a little hydrochloric 
acid is sometimes necessary and advantageous. When the 
amount of silver present is known, it need not be removed, 
but a correction can be applied to the final result instead. 
2Ag = Cu, or I per cent Ag = 0.3-per cent (eae 

When large amounts of arsenic, etc., are present, they may 
be only partially precipitated by the treatment with zinc, and 
may consequently, when the zinc is dissolved, react on the pre- 
cipitated copper and cause the solution of a small portion. 
With such ores more time should be allowed for the zinc to act 
before dissolving the excess, and also the first decantation 
should be made as soon as possible after the zinc has all been 
dissolved. An accurate assay can be made by this method in 
from 20 to 30 minutes. 


Whee WES ek eee 


COPPER. 157 


Battery-assay.—The amount of ore or substance to be 
taken will depend on the amount or copper which it contains. 
For the assays of a substance containing 5 per cent or less of 
copper 3 grammes should be taken, while for a substance con- 
taining over 60 per cent of copper 0.25 of a gramme will be 
sufficient. The usual amount is I gramme, but the assayer 
should use his judgment according to the amount of copper he 
thinks the substance contains. 

The substance is dissolved in the same manner described 
under the head of the cyanide-assay. It is then diluted with 
a little distilled water and in order to remove silver, if present, 
one or two drops of hydrochloric acid (in extreme cases the 
amount necessary may be larger, but care should always be 
exercised to avoid an excess, as this interferes with the results) 
are added, and the liquid filtered into a platinum dish of about 


- 60 to 70 cc. capacity. This dish is best made of the lightest 


platinum which will admit of ordinarily careful handling when 
filled with the solution. The platinum dish is then placed on 
a piece of copper or brass, connected with the negative or zinc 
element of the battery (a very good battery for this purpose is 
the ordinary Bunsen cell), while the liquid in the dish is con- 
nected with the positive pole either by a platinum wire attached 
to the positive pole and coiled in a horizontal spiral, or by a 
copper wire on which is hung a strip of platinum-foil the ends 
of which are immersed in the liquid. About 8 hours is the 
time usually required to complete the assay, the time of course 
depending on the amount of copper present and the activity of 
the electrical action. In order to determine if all the copper 
has been precipitated, a drop of the solution is removed from 


the dish by means of a pipette and tested with sulphuretted- 


hydrogen water. 

If this test shows all the copper to have been precipitated, 
the liquid is best removed from the dish by siphoning off by 
means of a bent-glass tube, the solution being replaced by dis- 
tilled water as fast as it siphons off, until it is washed suffi- 
ciently. When washed sufficiently the wires are removed and 
the dish is washed with alcohol, which is poured off and the 


158 A MANUAL OF PRACTICAL ASSA VING. 


contents dried by setting fire to the alcohol, which adheres to 
the sides, after which the dish with its brilliant coating of rose- 
red copper is weighed. The difference between the weight of 
the dish and its weight after the precipitation of the copper 
upon it represents the weight of copper precipitated, from 
which the percentage of copper can be calculated. The pre- 
cipitated copper should always be of a rose-red color, otherwise 
the result cannot be relied upon. Many of the different ele- 
ments, if in solution, will be liable to be precipitated together 
with the copper, and will affect the result, sometimes to a very 
great extent. Messrs. Torrey and Eaton of New York* have 
made a large number of tests with the cyanide and battery 
methods, and the results of their tests and the conclusions which 
they draw from them are that in all cases the cyanide method 
is more reliable than the battery method. When much arsenic, 
antimony, bismuth, etc., are present, a very good method of 
procedure is to treat the ore according to the method described 
under the head of cyanide-assay, and after dissolving the pre- 
cipitated copper with nitric acid, add sulphuric acid and evap- 
orate to expel the nitric acid, filter if necessary, and proceed to 
precipitate the copper by the battery. This method is prefer- 
able to the method described by Cairns,f and some other 
authors, of precipitating the metals of groups VI and VII by 
means of sulphuretted hydrogen and then dissolving the sul- 
phides of arsenic, antimony, and tin by the addition of caustic 
potash, on account of its greater speed and the less liability of 
loss of copper in manipulation. The use of sulphuretted hy- 
drogen is not only a source of annoyance and discomfort to the 
chemist, but, without very careful manipulation, introduces a 
liability of error owing to the difficulty of handling and wash- 
ing the precipitate. 

Taking all of the liabilities of error into consideration, the 
writer agrees with Messrs. Torrey and Eaton that the cyanide 
method is generally more accurate and preferable to the battery 
method. 


* See Engineering and Mining Journal for May and June 1885. 
+ See Cairns’ Quantitative Analysis 





COPPER. 159 


A very ingenious and simple apparatus for the estimation 
of copper by electrolytic deposition has been devised by Mr. 
A. H. Low of Denver, Colo.,* and is for sale by Eimer & 
Amend of New York. This apparatus not only shortens the 
time required for the determination of the copper, but consid- 
erably lessens the expense of apparatus, requiring no expensive 
batteries and platinum dishes. It is consequently to be highly 
recommended for use in a laboratory where a large number of 
determinations are required to be made daily by means of 
electrolytic deposition. This method fails when a large quan- 
tity of ferric sulphate is contained in the solution. 

Colorimetric Method.— This method is to be recom- 
mended for the estimation of copper in substances containing 
less than 2 per cent, as, for example, in slags from copper- 
smelting operations and in tailings from concentrating-works. 
The method was first suggested by Heine.t The method given 
here is a modification of Heine’s method. Where the amount 
of iron and alumina present is small, previous precipitation of 
the copper is not necessary, but in the case of slags and tail- 
ings, for which this method is particularly adapted, it would be 
impossible to wash out all of the copper salts with the small 
amount of wash-water which can be used; hence in this case 
previous precipitation of the copper is necessary. 

- The method consists essentially in converting the copper in 
the substance to be tested into ammonium cupric nitrate, and 
comparing the blue color produced with that produced by 
dissolving a known amount of copper in the same amount 
of acid and using the same amount of ammonia as is used in 
the regular assay. With each set of assays a separate stand- 
ard should be run, as the blue color is not constant, but fades. 
For the standard either an accurately weighed amount of pure 
copper can be taken, or the same amount of slag or tails 
as is used in the regular assay may be taken. Where the 
latter method is adopted, and it is generally preferable, as there 





* Proceedings of the Colorado Scientific Society, Vol. I. 
+ See Mitchell on Practical Assaying; Kerl’s Metallurgy of Copper. 


160 A MANUAL OF PRACTICAL ASSAYING. 


is less liability to error in weighing than where a small amount 
of.pure copper is taken, and it also introduces the same con- 
ditions into the standard as are present in the regular assay, of 
course the copper must have been previously accurately deter- 
mined in the sample from which the standard is weighed out. 
A few ounces of the material will last for a large number of 
assays. In order to make the assay, the amount of material 
for assay and of the standard are weighed out and treated in 
the same manner as described under the head of the cyanide- 
assay. When the precipitated copper has been thoroughly 
washed by decantation it is dissolved in a small amount of 
nitric acid (about 2 cubic centimetres is sufficient), and an excess 
of strong ammonia added (about 4 cubic centimetres), the acid 
and ammonia being pretty accurately measured. The solution 
after slight dilution with water is then filtered into a graduated 
tube for comparison, and washed. Two of these graduated 
tubes are necessary,—one for the regular assay and one for the 
standard. They should be of thin colorless glass and of the 
same internal and external diameter, and should also be pro- 
vided with a stopper, so that the solution may be thoroughly 
mixed by shaking. The assayer can prepare and graduate these 
tubes for his own use. 

The method of determining the percentage of copper pres- 
ent is best illustrated by an example: Suppose the material 
used for making the standard assay contained exactly I per cent 
of copper; then if a half gramme was taken, and after filtering 
into the tube and washing, the contents of the tube were 
diluted up to the 25-cc. mark with distilled water, each cc. of 
the solution would contain 5% milligramme of copper, or 0.2 
milligramme. The regular assay is then run, and after filter- 
ing into the tube the color of the solution is noted, and it is 
diluted with distilled water, shaking after each addition of 
water until the tint or color in the two tubes is the same when 
compared together against a white background. The height 
of the liquid in the tube is then noted. Suppose it reads 22 cc. 
Now, as each cubic centimetre of the standard solution contains 
0.2 milligramme of copper, each cubic centimetre of the solu- 


COPPER. 101 


tion in the other tube contains the same amount; hence 
20 0:2 — 4.4 millisrammes. 
Semmes Ore taken; 4.4 mgs. Cus 100: 4; +.== 0.88%Cu. 
Volumetric Iodide Method.—This method, as modified 


by A. H. Low,* is at present largely used in the West for 
the technical estimation of copper, and in the opinion of the 


author is one of the most accurate methods which we have. 

Prepare a solution of sodium hyposulphite containing 
19.59 grammes of the pure salt to the litre. Standardize as 
follows: Weigh out 0.2 gramme of pure copper-foil, place in 
a flask of about 250 cc. capacity, add 5 cc: of a mixture of 
equal volumes of concentrated nitric acid and water, and 
_ thoroughly boil off the red fumes. Remove from the lamp 
and add 20 cc. of acold saturated solution of zinc acetate. 
Heat to boiling, cool to the ordinary temperature, and dilute 
with water to about 50 cc. Add 3 grammes of potassium 
iodide, and shake the solution gently until the salt dissolves. 
The following reaction takes place: 

Cu(C,H,O,)2 + 2KI = Cul + 2KC,H,O, + I. 

The’ free iodine imparts a brown color to the solution. 
Titrate the solution immediately with the hyposulphite solu- 
tion until the brown color is nearly destroyed, add a few drops 
of starch solution, and continue the titration until the blue 
color disappears. When near the end allow a little time after 
the addition of each drop to avoid passing the end point. 
This titration should show each cc. of the hyposulphite solu- 
tion to correspond to about 0.005 gramme of copper; hence, 
in the assay of ores, etc., if 0.5 gramme of material is taken, 
each cc. of the hyposulphite will be equivalent to about I per 
cent of copper. 

The starch solution is prepared by boiling 0.5 of starch 
with water, diluting to 250 cc. with hot water and filtering. 
It should be used cold, and must be prepared frequently, as 
it does not keep well. The hyposulphite solution is quite 
stable, but should be restandardized from time to time. 

For the assay of ores and mattes, treat 0.5 gramme ina 





* Journal of the American Chemical Society, 1896. Engineering and 
Mining Journal, May 23. 1896. 


162 A MANUAL OF PRACTICAL ASSAYING. 


flask of 250 cc. capacity with 6 cc. of strong nitric acid, and 
evaporate nearly to dryness. Add 5 cc. of strong hydro- 
chloric acid, boil, and as soon as complete solution is effected, 
add 5 cc. of strong sulphuric acid. Heat strongly, best by 
manipulating the flask in a holder over a small naked flame, 
until the more volatile acids are expelled and sulphuric fumes 
are evolved freely. Cool, add 20 cc. of cold water, and heat 
to boiling to effect complete solution. Filter into a small 
beaker, wash with hot water, and endeavor to keep the volume 
of the filtrate down to 50 or 60 cc. Place in the beaker two 
pieces of aluminium about one and a half inches square, one 
sixteenth of an inch thick, with the four corners bent for one- 
fourth inch, alternately up and down, at right angles. Add 5 
cc. of strong sulphuric acid, cover the beaker, and boil for 
seven minutes. Unless the bulk of the solution is excessive, 
this will generally be sufficient to precipitate all the copper. 
Transfer the solution back to the original flask, rinsing in with 
hot water as much of the copper as possible. Allow the 
copper in the flask to settle, and decant the liquid through a 
filter. Wash the copper two or three times, retaining it as 
completely as possible in the flask. Pour upon the aluminium 
in the beaker 5 cc. of a mixture of equal volumes of strong 
nitric acid and water, warm gently until the copper is dissolved, 
and pour the solution through the filter, receiving the filtrate 
in the flask containing the main portion of the copper. Heat 
the contents of the flask to dissolve the copper, add 0.5 
gramme of potassium chlorate, and boil to insure the oxidation 
of any arsenic present to arsenic acid. Place the flask under 
the funnel, wash the beaker, filter thoroughly with hot water, 
and boil the contents of the flask to remove every trace of 
red fumes. All the copper is now in the flask as nitrate, 
Add the zinc acetate, and proceed from this point precisely 
as described with the original nitrate of copper solution in the 
standardization of the hyposulphite, finally calculating the 
percentage of copper present from the amount of standard 
hyposulphite used. 

Silver, lead, and bismuth do not interfere, except that the 
latter is liable to mask the end-point before adding the starch. 


CHAPTER XIV. 
BISMUTH (Bi). 


ABOUT the only determinations of bismuth which the metal. 
lurgical chemist will be called on for are in refined lead, base 
bullion, and occasionally ores. The methods given are ab- 
stracted from a paper by L. G. Eakins.* 

Refined Lead.—After rolling into thin sheets the lead is 
cut up into small pieces, 75 gms. of which are introduced into 
a beaker, and go cc. of nitric acid (1.42 sp. gr.) and 400 cc. of 
water are added. The solution is heated, replacing the evap- 
orated water, and as soon as everything is dissolved the solu- 
tion is transferred to an 810 cc. graduated flask containing 20 ce. 
of strong sulphuric acid somewhat diluted. The flask is filled 
to the mark, stoppered, and well shaken. After allowing the 
precipitate to subside somewhat, the solution is filtered through 
a dry rapid filter into a 529 cc. flask, which is filled exactly to 
the mark. The whole operation is performed so rapidly that 
the change in volume due to cooling can be neglected. The 
following calculation shows the amount of material the 529 cc 
of solution represents: 


Volume of liquid and precipitate..... rae 810.00 cc. 
Volume of lead sulphate from 75 gms. of lead 16.875 cc. 


era euiic OL MQUIC . oa. sie oe opie vies FOR 25 Co 
Then 





ey tel 2 58s 200: 75 112 (Ava 50.0219, ), 
or in round numbers 50 gms. of the lead. 
The solution is evaporated in a large beaker, and when 
sufficiently concentrated is transferred to a porcelain casserole 


* Proceedings of the Colorado Scientific Society, Feb. 1895. 
163 


164 A MANUAL OF PRACTICAL ASSAYING. 


and evaporated until SO, fumes are freely evolved. After 
cooling it is diluted with cold water to 125 cc., and boiled 
briskly for a few minutes to insure re-solution of all the bismuth 
sulphate. 

After cooling, filter, washing the precipitated lead sulphate 
with dilute sulphuric-acid water. Warm the filtrate and pass 
sulphuretted hydrogen gas for 1oto 15 minutes; allow to stand 
warm until sulphides have settled, filter, and wash with hot 
water. Return the precipitate to the beaker in which the pre- 
cipitation took place, and add 15 to 20 cc. of yellow potassium 
sulphide. Heat to boiling, dilute, and decant through the same 
filter as used for filtration of the sulphides; repeat treatment 
with fresh alkaline sulphide; finally transfer the precipitate to 
the filter, and wash with water containing some of the alkaline 
sulphide. Place the filter and precipitate in the same beaker, 
add 5 cc. of strong nitric acid diluted to 25 cc., warm to effect 
solution, and filter into a porcelain dish; burn papers at a low 
heat, adding the ash to the solution; add 3 cc. of strong sul- 
phuric acid, and evaporate to fumes of SO,. Cool, dilute, boil, 
allow to cool, filter, and wash with dilute sulphuric acid. To 
the filtrate add solution of sodium carbonate until the solution 
is slightly alkaline (a drop of methyl orange is a good indicator), 
and add a few drops of a strong solution of potassium cyanide. 
Boil for a few minutes, allow to stand warm until the precipi- 
tate has settled and the supernatant liquid is clear. Filter 
through a quite close paper, washing with warm water ; dissolve 
the precipitate in warm dilute nitric acid; add ammonia to 
alkalinity, and 3 to 5 cc. of ammonium-carbonate solution. 
Heat to boiling, and allow to stand warm until the bismuth car- 
bonate has settled; filter, and wash. Dry filter and precipi- 
tate, remove the latter as completely as possible, burn filter and 
add its ash to precipitate, ignite in a small porcelain crucible at 
a low red heat, and weigh as Bi,O,. 

Lead Bullion.—Treat as above until measured portion of 
clear solution is obtained. The solution is now rendered 
ammoniacal, 50 cc. excess of ammonia is added, and hydrogen 
sulphide is passed nearly to saturation when 20 cc. more of 


Be L.# 


- 


BISMUTH, 165 


ammonia is added, and the whole is allowed to stand warm 
until the precipitate has completely settled. Filter and wash 
slightly; place filter and precipitate in a beaker, add 15 cc. of 
strong nitric acid, dilute to 60 cc., warm until sulphides are 
decomposed, and filter into a porcelain dish. Burn filter and 
add its ash to dish, then Io cc. of strong sulphuric acid, and 
evaporate to fumes of SO,. From this point on the determina- 
tion is as with refined lead, except that a larger quantity of the 
alkaline sulphides are required. At the second evaporation the 
sulphuric acid used should be increased to 6 cc. When pre- 
cipitating with sodium carbonate and potassium cyanide enough 
of the latter must be added to bring all of the silver, copper, 
and cadmium into solution. 

Ores.—For the estimation of bismuth in lead ores the fol- 
lowing will answer: Make a number of fusions as in the fire- 
assay for lead (see page 137), combine the buttons, and treat 
exactly as in the assay of base bullion for bismuth. 

For ores other than lead ores add to each charge about one 
fifth of the weight of ore taken of some bismuth-free lead salt, 
as carbonate, fuse, and proceed with the lead buttons as in the 
case of lead bullion. 

Whilst this method is not strictly accurate, it will answer 
for all technical purposes. 


CHAP DE Ree: 
CADMIUM (Ca). 


CADMIUM may be determined gravimetrically by precipi- 
tation as CdCO,, ignition to CdO, and weighing as such, or it 
may be determined volumetrically by means of a standard 
solution of potassium ferrocyanide. 

There are several other methods, both gravimetric and 
volumetric, for which see Fresenius, Rose, etc. 

Gravimetric Determination.—Decompose the ore with 
nitrohydrochloric acid, evaporate nearly to dryness to drive 
off the nitric acid, leaving but a small quantity of free hydro- 
chloric acid present. Dilute with warm water, filter, and wash 
thoroughly with hot water. Through the filtrate pass a 
rapid current of sulphuretted hydrogen until all members of 
the sulphuretted-hydrogen group are completely precipitated. 
The solution should not contain a large excess of hydrochloric 
acid; if it does the cadmium will fail to precipitate. Filter 
off the precipitated sulphides, and wash with sulphuretted- 
hydrogen water. Dissolve the precipitated sulphides in hot 
hydrochloric acid, and boil. If lead is present some will pass 
into solution, and can be removed by precipitation with sul- 
phuric acid. Filter and. wash. The filtrate will contain the 
cadmium asa chloride. Precipitate the cadmium with a slight 
excess of potassium carbonate (pure), filter, and wash precipi- 
tate thoroughly with warm water. Dry the precipitate, and 
when dry remove carefully from the filter-paper, introducing 
it into a weighed crucible. Moisten the filter-paper with a 
strong solution of ammonium nitrate, wrap it in a spiral of 
platinum wire, and ignite over an alcohol flame, allowing the 
ash to fall into the crucible. The cadmium carbonate adhering 
to the filter-paper is liable to be reduced by the carbon of 
the filter, and volatilized ; hence the addition of ammonium 


nitrate, and the care required in ignition, ‘Transfer all the ash 
166 


CADMIUM. 167 


to the crucible, and ignite to constant weight. Care should 
be exercised during ignition that the cadmium oxide is not 
reduced. If reduced some will be volatilized and lost. Weigh 
the cadmium oxide, and calculate the percentage of cadmium. 

The results are liable to be a little low. 

Volumetric Determination.—This requires a standard 
solution of potassium ferrocyanide of about two-thirds the 
strength of the solution used for the determination of zinc. 
If its standard for zinc is known its standard for cadmium may 
be calculated as follows: Let a= mgs. of zinc which 1 cc. of 
ferrocyanide solution is equivalent to, and 4 = mgs. of cadmium 
which 1 cc. of the solution should precipitate; then 


Tz0cmnol. wt. 271) : 224(mol. wt..2Cd) :: @: x. 


It is best to standardize the solution with a solution of 
cadmium known to contain a certain weight of cadmium. 

The titration is performed in the same manner as in the 
determination of zinc, using uranium acetate as an indicator. 
The solution should not contain a large excess of hydrochloric 
acid, as cadmium ferrocyanide is soluble in hydrochloric acid. 
The analysis is performed as follows: Treat I gramme of ore 
in the same manner as in the determination of zinc (see Chap- 
ter XXI), and filter off the precipitated oxides. Neutralize 
the filtrate with hydrochloric acid, and add a slight excess of 
acid. Dilute with warm water, and pass a rapid current of 
sulphuretted hydrogen. Filter off the precipitated sulphides, 
wash with sulphuretted-hydrogen water, and dissolve the pre- 
cipitate in dilute hot hydrochloric acid. Dilute, and if copper 
is present precipitate it with test-lead or aluminium-foil. The 
solution is now ready for titration with the standard solution 
of potassium ferrocyanide. 

The filtrate from the precipitated sulphides may be used 
for the determination of zinc, and the copper (if precipitated 
on aluminium-foil) may be determined as described in Chapter 
XIII. 

The method is rapid, and gives results which answer all 
requirements for technical purposes. 


CHAPTER XVI. 
IRON (Fe). 


WHILST many different methods have been proposed for 
the determination of iron, the three following are the only ones 
in general use in the United States: 

1. By precipitation with ammonia, filtration and ignition to 
ferric oxide, weighing as such ; 

2. Volumetrically, by means of a standard solution of po- 
tassium permanganate (Marguerite’s method) ; 

3. Volumetrically by means of a standard solution of po- 
tassium bichromate (Peeny’s method). 

The chemist may have occasion to use all of these 
methods, as one very frequently gives good results where the 
others fail. Sometimes a combination of the first and second 
or rst and third may be employed to advantage. When the 
iron is to be determined by the first method the solution from 
which the iron is precipitated should first be freed from 
alumina, chromium, manganese, titanium, lead, arsenic, etc., 
which are wholly or in part precipitated together with the 
ferric hydrate. As this is not always possible, especially in 
technical determinations, a combination of this method with 
one of the volumetric methods may be employed as follows: 
The iron, either in a hydrochloric- or sulphuric-acid solution 
(sometimes it may be an acetic-acid solution when a basic- 
acetate precipitation has been made as described under the 
head of Alumina), is precipitated by adding ammonia in 
excess to the warm solution and the solution brought to a 
boil. It is then filtered through a ribbed filter-paper and 


washed. As this precipitate is exceedingly bulky and difficult 
168 





TRON. 169 


to wash, a filter-pump may here be used to advantage. It 
should be washed with warm water until the washings show 
only a faint trace of chlorides or sulphates, as the case may be. 
It is then dissolved on the filter-paper directly into a flask 
with warm diluted hydrochloric or sulphuric acids. It may 
then be reduced and determined volumetrically by either the 
second or third methods, as the case may be. If dissolved 
with sulphuric acid, it may be determined by either of these 
methods; if dissolved by hydrochloric acid, preferably by the 
bichromate method. 

The second method depends upon the fact that when a so- 
lution of potassium permanganate, which has an intense color, 
is dropped into a solution of ferrous oxide it gives up a por- 
tion of its oxygen, being decomposed into salts of manganese 
and potassium, until the ferrous oxide is completely converted 
into ferric oxide. The moment this conversion is complete 
the permanganate imparts a pink color to the solution. The 
reaction which takes place is as follows: 


10oFeSO, + 8H,SO, + K,Mn,0, = | 
5Fe,(SO,), + 2MnSO, + K,SO, + 8H,0. 


From this it will be seen that in order to determine the 
amount of iron in solution it will only be necessary to know 
what amount of iron one cubic centimetre of the perman- 
ganate solution will oxidize from the ferrous to the ferric 
form. 

A normal solution of permanganate is a solution of which 
I cubic centimetre is equal to or converts 10 milligrammes 
of iron from the ferrous to the ferric state. To prepare such 
a solution, dissolve 12 grammes of pure crystallized potassium 
permanganate in 2030 cc. of distilled water. The amount of 
water will vary slightly with different permanganates, so that 
the chemist will have to determine for himself the exact amount 
with each new bottle of permanganate he uses. This solution 
should be placed in a stoppered bottle and shaken from time 
to time until ready for use. It is best to make up the solution 


170 4A MANUAL OF PRACTICAL ASSAYING. 


at least forty-eight hours before standardizing. This solution 
may be standardized in two ways: 

Ist. By means of metallic iron. 

The iron employed for the purpose is usually fine piano- 
forte wire, which contains 99.7 per cent iron. This should be 
rubbed with sand-paper until bright, in order to remove dust 
and shellac, with which it is sometimes covered, etc., before 
weighing out. It is best to weigh it out on the button-bal- 
ance, two portions being taken of about 150 and 200 milli- 
grammes, respectively. These portions are each introduced 
into a flat-bottomed flask (250 cc.) and dissolved with dilute 
sulphuric acid by gently warming. Many chemists (see Fre- 
senius, Cairns, etc.) use a valve-flask for this purpose, to pre- 
vent the oxidation of the iron during solution. The writer 
prefers to dissolve.without going to the trouble of preparing a 
valve-flask, and afterwards reduce the small amount of iron 
which may have been oxidized, by the addition of some pure 
granulated zinc. This reduction takes but a few minutes. 
When the iron is all reduced, which may be determined by 
removing a drop of the solution on a glass rod and testing it 
ona porcelain plate with a drop of ammonium-sulphocyanate 
solution (if the iron is all reduced to the proto state the drop 
will remain colorless, whilst if any ferric oxide is present the 
drop will turn red, the depth of the color depending on the 
amount of ferric iron present), the contents of the flask are 
diluted, by the addition of cold distilled water, and the solu- 
tion decanted off from the zinc into a large beaker, or prefer- 
ably an ordinary glass battery-jar, the jar being much less 
liable to breakage in subsequent stirring of the solution. The 
flask and zinc are well washed, the washings being transferred 
to the jar. The solution is then diluted up to about 700 cc. 
(it is a good plan to scratch a mark on the side of the jar at 
this point), and about 20 cc. of dilute sulphuric acid are added. 
In making subsequent determinations it is better to use the 
same or a similar jar, and always fill to the same point so as 
to have the same bulk of solution. Sometimes minute par- 
ticles of zinc will be decanted over with the washings, but 


ees Phe 


IRON. 17% 


these will quickly be dissolved by the excess of sulphuric acid. 
As soon as all effervescence of gas has ceased,—the solution 
should not be allowed to stand too long, as some iron is liable 
to be oxidized by contact with the air,—the solution is ready 
to titrate with the previously prepared permanganate solution 
which is run in drop by drop from a burette, with constant 
stirring, until the color (which disappears rapidly at first, and 
then more slowly) finally becomes permanent, and remains so 
for one minute. The final color should be a light pink, and the 
chemist should note this color and bring his subsequent titra- 
tions to the same tint. The titrations should be performed in 
a good light and with a white surface (piece of paper) under- 
neath the jar. Note carefully the quantity of permanganate 
solution used, and calculate its value or standard as follows: 
Suppose 0.200 gramme of iron were taken and 19.5 cc. of the 
permanganate solution was used: then 


0.1994 + 19.5 = 0.010225 +. 


Hence 1 cc. of permanganate solution corresponds to .01022 
gramme of iron. 

The results obtained on the two samples of iron wire taken 
should not differ more than one tenth of a cubic centimetre. 
If the difference is greater than this more trials should be 
made. 

The other method of standardizing the solution is by 
means of oxalic acid. The objection to this method is the 
uncertainty of procuring a normal acid. When oxalic acid is 
used the crystals should be kept in a tight-stoppered colored- 
glass bottle, and each bottle should be tested with some per- 
manganate solution, the standard of which has been previously 
determined, to determine if it is normal. The oxalic method 
has the advantage that it is more rapid than the iron-wire 
method. To standardize the solution by this method weigh 
out about 250 milligrammes of oxalic acid on the button- 
balance, the exact amount taken being immaterial, so that the 
exact weight is known. Dissolve in water (about 100 cc.), and 
add 6 to 8 cc. of pure concentrated sulphuric acid. Heat to 


172 A MANUAL OF PRACTICAL ASSAYING. 


about 60° to 70° C., and add permanganate solution until the 
color is permanent. The color will disappear very slowly at 
first, but after a few cubic centimetres of the permanganate 
solution have been added, it will disappear rapidly. After the 
first faint permanent tint has formed, add one or two drops of 
permanganate in excess (one or two drops having previously 
been determined to be the amount required to impart a faint 
tint to 600 cc. of distilled water) on account of the greater bull 
of solution used when standardizing by iron wire. 

By comparing the equation previously given with the fol- 
lowing equation, which represents the oxidation of oxalic acid, 


5(H,C,0,2H,O) + 3H,50, + K,Mn,O, = 
10CO, + 2MnSO, + K,SO, + 18H,O, 


it will be seen that the same quantity of potassium perman- 
ganate is required to oxidize one molecule of oxalic acid whose 
molecular weight is 126, or two atoms of iron (in the form of 
monoxide) whose molecular weight is 112. Consequently we 
have the equation assuming 0.250 gramme of oxalic acid were 
taken: 

126: 112 3: .250: .222-4. 


In other words, the 250 milligrammes of oxalic acid taken rep- 
resented .222-+ grammes of metallic iron. Suppose that 21.7 
cc. of permanganate solution were used, then one cubic centi- 
metre of permanganate solution would correspond to .o1023 + 
grammes of iron. 

In practice the writer has usually standardized the solution 
once with iron wire and then checked the result with oxalic 
acid, using an acid which was known to be normal. 

Provided the proper precautions are obsetved, iron may be 
determined in a hydrochloric-acid solution by means of 
standard potassium-permanganate solution, although most 
authors claim that this method is not accurate on account of 
the following reaction, which takes place if the solution is at all 
warm : 


K,Mn,O, -+ 16HCI = 2KCl + 2MnCl, + 8H,O + 10Cl. 


aeeiaa a 4 to 


IRON. 173 


Some of the chlorine set free will convert the ferrous iron pres- 
ent into ferric; but some will usually escape, and the results 
obtained will consequently be too high. 

The writer has found by experience that if only a small 
quantity of hydrochloric acid is present and the solution is ex- 
tremely dilute (700 cc.) and cold, and moreover contains a large 
excess of sulphuric acid (usually 20 cc. concentrated acid), that 
the results obtained are as reliable as when sulphuric acid has 
been used as the solvent. As a further precaution some 
chemists add a few cubic centimetres of a saturated solution 
of manganous sulphate before titration. The writer has 
generally found this latter precaution unnecessary, provided 
the above conditions were carried out; but as the addition of 
manganous sulphate can do no harm, it is well to use it when 
the operator is in doubt or when a considerable amount of 
hydrochloric acid has been used. 

The third method depends on the fact that if potassium 
bichromate is added to a solution of a ferrous salt in the pres- 
ence of a strong free acid, the ferrous oxide is converted into 
ferric oxide, as is shown by the equation 


fee lec O - 14HCl = 3Fe.Cl, + 2KCl+ CrCl, + 7H.0, 


which shows that I or 295.18 parts of potassium bichromate 
will convert 6 equivalent or 336 parts of iron to the ferric state 
(295.18 being the molecular weight of K,Cr,O, and 336 being 
6 times the atomic weight of Fe). In practice a half-normal 
solution, or a solution of which one cubic centimetre is equal 
to 0.005 gramme of iron, is usually used. To prepare this 
solution dissolve 8.785 grammes of pure potassium bichromate 
in two litres of water. The solution is best standardized by 
means of iron wire, dissolving the wire either in hydrochloric 
or sulphuric acids. The solution is then reduced and trans- 
ferred to a suitable vessel for titration, some free acid being 
added. The bichromate solution is dropped in from a burette, ° 
the liquid being constantly stirred with a glass rod. The 
liquid, which is at first nearly colorless, speedily acquires a 


174 A MANUAL OF PRACTICAL ASSA YING. 


pale-green tint, which changes gradually to a darker green. 
A small drop of the liquid is now from time to time taken out 
by means of the stirring-rod and tested on a porcelain plate 
with a drop of potassium ferricyanide (free from ferrocyanide), 
which should not be too strong or it will give a red precipitate. 
When the blue color produced by the action of a ferrous salt 
on the ferricyanide begins to lose the intensity which is 
exhibited on the first trials and becomes quite faint, the 
addition of bichromate solution is proceeded with more care- 
fully. When the test no longer produces a blue color the 
oxidation is complete. From the remarkable delicacy of the 
reaction the exact point may be easily hit toa drop. After a 
little practice a large number of tests will seldom have to be 
made, as the operator may determine, from the manner in 
which the green color of the solution deepens, about how 
much bichromate it will be safe to add before testing. Many 
authors (Fresenius, Cairns, etc.) recommend the use of a 
solution one tenth as strong as the regular solution for finish- 
ing the titration. In ordinary practice this is found to be 
unnecessary where a solution as dilute as the one recommended 
is used. 

After the titration is completed, take the reading of the 
burette and determine the value of one cubic centimetre of 
the solution in the same way as described for the permanganate 
solution. It is best to weigh out two portions of the iron wire 
and standardize the solution in duplicate, as is done in the case 
of the permanganate solution. 

For determining the iron by this method it may be reduced 
to the ferrous state either by means of zinc or by means of a 
solution of stannous chloride added in slight excess, the excess 
peing taken up by means of mercuric chloride. This latter 
method has the advantage that the reduction may be per- 
1ormed in a few moments, thus greatly reducing the time 
required to make a determination. It may also be employed 
to advantage when zinc free from iron and arsenic cannot be 
obtained, which may sometimes happen. If proper care is 
used in the reduction the result will agree perfectly with 


IRON. 175 


those obtained by reduction with metallic zinc. The only 
point to be observed is that the solution of stannous and mer- 
curic chloride should not be too strong, and only a slight excess 
should be used. The operator, after a little practice, will have 
no difficulty in observing these conditions. The best form, 
and, on the whole, that which gives the most rapid reduction, 
when zinc is used to reduce the iron, is pure granulated zinc. 
The granulations should be quite heavy, otherwise small por- 
tions will become detached and pass over with the solution for 
titration into the jar. The granulated zinc may be made from 
pure bar zinc by melting in a crucible, placing a few lumps of 
charcoal on the surface of the zinc, and pouring into cold water 
after skimming. 

The solution may also be reduced by boiling in a flask with 
granulated zinc which has previously been amalgamated with 
mercury. In order to amalgamate the zinc place it in sul- 
phuric acid for a few moments, remove, and wash with water; 
then place in a bottle containing clean mercury and sulphuric 
acid, and shake. This method of reduction has the advantage 
that less zinc is consumed than in the case where raw zinc is 
used, and also that if, in transferring the solution from the flask, 
some pieces of zinc pass over, they need not be removed before 
the titration is proceeded with, as hydrogen 1s not evolved from 
the amalgamated zinc in a cold dilute solution. It has the dis- 
advantage that more time is required to reduce the solution. 
Where zinc free from impurities cannot be obtained, the solu- 
tion may be reduced in the following manner: Prepare some 
cubes of zinc about one-half inch square, and thoroughly amal- 
gamate them with mercury. In each of the flasks containing 
the solution of iron to be reduced place a strip of platinum-foil 
about three inches long and three quarters of an inch in width, 
and on this place a cube of the amalgamated zinc. In order 
to have the foil work well it should be cleaned and its surface 
roughened. A strong current of gas should be induced by con- 
tact between the zinc and platinum. A convenient form of 
apparatus for this reduction is described in Vol. XV, Trans- 
actions of the American Institute of Mining Engineers. A 


OS a 


176 A MANUAL OF PRACTICAL ASSA YING, 


good vessel to perform this reduction in is the ordinary pound 
bottle that caustic potash and other reagents are put up in by 
the manufacturers. It has been found by experiment that 
amalgamated zinc will not give up its iron until it is nearly 
dissolved. The disadvantage of this method is the length of 
time it requires to reduce a solution—from 6 to 20 hours gen- 
erally being necessary. Several other methods of reduction 
are described by different authors, but the above are sufficient 
fer every case likely to occur in practice,and are among the 
best. 

The exact method to be pursued in making a determination 
will depend on the character of the substance. 

Iron Ores.— Most iron ores will yield their iron by simple 
boiling with acids. Hydrochloric acid is the acid usually em- 
ployed. Nitric acid is to be avoided, and this is especially the 
case where the iron is to be determined volumetrically by either 
of the above methods, for, if any nitric acid (which is an oxi- 
dizing agent) is present, reduction and subsequent titration will 
be impossible. If an ore is not decomposed by simple boiling 
with hydrochloric acid it may be treated with all three acids 
in the manner described for sulphide ores, 

Usually from 0.5 to I.o gramme of ore is dissolved in a 
small casserole or beaker, a small vessel always being desirable, 
as it avoids the use of a large excess of acid; and when all the 
iron is in solution, which may be determined by the appearance 
of the insoluble residue, the contents of the vessel are washed 
into a flask and reduced by some one of the methods described 
above, and the iron determined volumetrically by either of the 
standard solutions in the manner described above. 

For the determination of the iron the filtrate from the silica 
can be taken, always provided nitric acid has not been used in 
dissolving. 

In some rare cases an ore may be encountered which will not — 
yield all of its iron by treatment with acids. In such a case a 
very good method of procedure is to filter off and fuse the in- 
soluble residue with potassium bisulphate (see Silica, Chapter 
I), and add the product of the fusion, after solution in water, 


IRON. 177 


or water together with a few drops of hydrochloric acid, to the 
filtrate containing the greater portion of the iron. 

In the case of chromic and titaniferous iron ores which will 
not readily dissolve by treatment with acids, fuse the insoluble 
residue as described in Chapter I, combine the filtrate from the 
insoluble residue and the iron, determine the iron as above in 
the combined filtrates. 

Manganese Ores.—Determine iron in the same manner as 
in iron ores. 

Limestone, Clay, Cement, etc.—The iron is best deter- 
mined in the filtrate from the silica (when the insoluble residue 
has been fused, the filtrate from it should be added to the fil- 
trate from the fusion) by heating it and precipitating the iron 
with ammonia as ferric hydrate. If the iron alone is required 
this precipitate should be boiled in the beaker for a few min- 
utes and then filtered and washed with boiling water. When 
the washings no longer show the presence of chlorides (this 
can be determined by obtaining a small portion of the wash- 
ings in a test-tube, acidifying with nitric acid, and adding a 
drop of silver-nitrate solution, which should not give a white 
precipitate if the chlorides are all removed), the precipitate can 
be dissolved with warm dilute sulphuric acid directly into a 
flask, the iron being reduced and determined as before. Where 
lime, magnesia, etc., are not to be determined in the filtrate, the 
precipitate need not be washed to the extent of removing the 
last traces of chlorides. | | 

When alumina is to be determined, proceed in the manner 
described in Chapter XVII, on Alumina. 

Sulphide Ores, Mattes, etc.—The same method may be 
pursued in the case of all sulphide ores, no distinction being 
made between copper ores, lead ores, iron ores, etc., except that, 
when the amount of iron present is small, larger quantities 
should be taken. Dissolve 0.5 gramme of ore in a small casse- 
role with 2 cc. of strong hydrochloric, 5 cc. strong nitric, and 
about 8 cc. dilute sulphuric acids added in the order named. 
The sulphuric acid should be about 60 per cent concentrated 
acid and 40 per cent water. A flat-bottomed flask can also be used 


178 A MANUAL OF PRACTICAL ASSA YING. 


for the solution, the subsequent reduction being performed in 
the same flask. Heat on a sand-bath or iron plate until dense 
white fumes of SO, are evolved. Continue to heat for about 
two or three minutes, in order to be sure of removing the last 
traces of nitric acid; remove from the source of heat, cool, and 
dilute to about 30 cc. If a casserole was used for solution, 
wash the contents into a flask, reduce, and determine volumet- 
rically. In the case of lead ores the solution is best reduced 
by means of metallic zinc, on account of the sulphate of lead 
which is formed. The zinc reduces this lead sulphate to me- 
tallic lead, resulting in the liberation of any small amount of 
ferric sulphate which it might have held mechanically so that it 
would not have been reduced, thus giving too low a result. 
When an ore contains arsenic or antimony the reduced solution 
cannot be safely titrated by means of potassium permanganate. 
In this case it is best to first precipitate the arsenic or antimony 
with sulphuretted hydrogen, filter off the precipitated sul- 
phides, and determine the iron in the filtrate. In the case of 
copper ores containing large percentages of copper, it is best 
to first precipitate the iron with ammonia and determine as in 
the case of iron in limestones, as copper will interfere with the 
titration and give too high results. 

Oxidized Ores of Lead, Silver, Copper, ete.—Treat in 
the same manner as an oxidized iron ore. 

Slag.—If the sample has been taken by suddenly chilling it 
(see Chapter I, on Silica), it may be treated as follows: Weigh 
out one half gramme of finely pulverized slag into a casserole 
of about 100 cc. capacity, moisten with about 7 cubic centi- 
metres of water, and stir with a glass rod. Then add about 5 
cc. hydrochloric acid and stir again with a glass rod in order to 
break up any clots which form and stick to the bottom. Heat 
to boiling, and stir from time to time, if necessary. When the 
slag is decomposed, which may be determined by moving the 
glass rod around the bottom of the casserole to see if any gritty 
substance is encountered. If no grit is encountered and the 
insoluble portion appears like flocculent silica when the solu- 
tion is stirred with the rod, the slag is decomposed. Usually 


TRON. 179 


there will be some black specks seen floating on the surface of 
the liquid, but they may be disregarded, as they consist princi- 
pally of lead sulphide. The contents of the casserole are now 
diluted with water and a few cubic centimetres of dilute sul. 
phuric acid added, and then some pure zinc to reduce the iron, 
the casserole being covered with a convex watch-glass. After 
the iron is reduced, which will only require a few minutes, as 
most of the iron was originally present as ferrous iron, and if 
the solution is performed rapidly, but a small portion of it will 
have become oxidized ; it can be determined by either of the 
methods of titration given,—standard bichromate or perman- 
ganate of potassium solution. Or the iron may be reduced by 
means of stannous chloride as before described, and determined 
with standard bichromate solution. A determination may be 
made in from ten to fifteen minutes, according to the method 
employed. When the sample was not so taken that the slag 
will decompose in hydrochloric acid a cintering fusion may be 
made on 0.5 gramme (see Chapter I), the fusion being 
dissolved in water and hydrochloric acid, and the iron deter- 
mined as above, or the iron may be determined in the filtrate 
from the silica. If the iron is determined in the filtrate from 
the silica, care should be taken not to heat the mass, after 
evaporation to dryness, much above 110° C., otherwise chloride 
of iron will be volatilized. Objection may be taken to the 
above rapid method on the ground that it is not absolutely 
accurate However, with ordinary care in manipulation dupli- 
cates will agree within two tenths of a per cent, and the 
method certainly gives results sufficiently accurate for the con- 
trol of the workings of the furnace in a metallurgical works. 
The writer has frequently examined the insoluble residue from 
the silica determination for iron by fusing, without finding 
more than a trace, and generally without being able to detect 
any ferrous oxide. On account of the rapidity of this method 
it is invaluable to the lead or copper metallurgist for the con- 
trol of the workings of the furnace. 

Fused Ores, Fused Flue-dust, etc.— These will fre- 
quently decompose as perfectly as a slag if sampled by the 


180 A MANUAL OF PRACTICAL ASSAYING. 


rod (see Part II, Chapter I). In such a case the iron may be 
determined as above. When the insoluble residue is gritty 
and contains iron it should be fused either with acid sulphate 
of potassium or carbonate of soda, the determination then 
being proceeded with as described under the head of Iron Ores, 
the filtrate from the insoluble residue and the silica being com- 
bined. ; 

Pig-iron, etc.—Most pig-irons, steels, etc., will give up 
their iron by simple heating with dilute sulphuric acid. The 
iron may then be determined as easily as in the case of piano- 
forte wire, it however being a good plan where 0.5 gramme 
is taken to dilute the solution up to 500 cc. with distilled 
water, draw off two or three portions of 100 cc. each with a. 
pipette, reduce each portion, and determine. A very good plan 
is to titrate one portion, then add the next portion to the 
same solution and titrate, then add the third portion, and take 
the total reading of the burette, making the calculation of the 
percentage on the basis of three fifths of a gramme of sub- 
stance taken. 

In the case of ores, etc., containing arsenic and antimony 
the following rapid method will serve for all technical deter- 
minations: Decompose as described above, and reduce the 
iron with granulated zinc. When the iron is all reduced filter 
rapidly, and wash thoroughly with water. The arsenic and 
antimony will be precipitated by the zinc and remain on the 
filter. The filtrate containing the iron can now be safely 
titrated as above. | 

Zimmermann-Reinhardt Method.—The following modi- 
fication of this method* is extensively used in the Lake 
Superior iron region for the estimation of the iron in ores. As 
the method is extremely rapid (a determination can be made 
in IO minutes) and sufficiently accurate for all commercial pur- 
poses, it is highly recommended. 

The following solutions are necessary : 

Stannous Chloride.—One pound of stannous chloride is 





* Journal of the Am. Chem. Society, Vol. XVII, No. 5, May, 1895. 


IRON. 1804@ 


dissolved in one pound of hydrochloric acid (sp. gr. 1.2), slightly 
diluted with water, and when solution is effected, is diluted to 
two liters. 

Hydrochloric Acid.—Made by mixing equal volumes of 
strong acid and water (sp. gr. 1.1). 

Mercuric Chloride.—A saturated solution is prepared by 
dissolving the salt in hot water, and, after allowing to cool and 
crystallize, filtering. 

Manganous Sulphate.—One hundred and sixty grammes 
of manganous sulphate are dissolved in water and diluted to 
1750 cc. To this are added 330 cc. of phosphoric acid (syrup 
1.7 sp. gr.) and 320 cc. of sulphuric acid (sp. gr. 1.84). 

One-half gramme of ore is treated in a beaker with two 
and a half cc. of stannous-chloride and ten cc. of the hydro- 
chloric-acid solutions. The beaker is covered with a watch- 
glass and its contents allowed to boil gently on an iron plate 
until the ore is completely dissolved. As soon as solution is 
effected stannous chloride is run in from a burette, drop by 
drop, until the iron is completely reduced, the reduction being 
indicated by the disappearance of the greenish-yellow color. 
The solution is now slightly oxidized with a few drops of the 
potassium-permanganate solution and kept warm. Just before 
titration the final reduction is effected by the addition of a 
drop or two of the stannous-chloride solution, avoiding any 
considerable excess. The sides of the beaker are washed down 
and five cc. of the mercuric-chloride solution are added to take 
up the excess of stannous-chloride. The contents of the beaker 
are now washed into a 500 cc. beaker, in which has been placed 
six to eight cc. of the manganous-sulphate solution and about 
Aoo cc. of water. 

The titration is now proceeded with, using a standard solu- 
tion of potassium permanganate (see page 169). 

Ores Containing Organic Matter.—If the amount of 
organic matter is small it may be oxidized, during solution, by 
the addition of potassium chlorate. If the amount is large it 
is best to burn off and follow with the regular method. 


1806 A MANUAL OF PRACTICAL ASSAYING. 


Pyritous Ores.—These may be treated as in the case of 
ores containing organic matter. 

Magnetites.—As magnetites are frequently difficult to 
decompose, it is best to make a fusion with mixed carbonates, 
and, after dissolving from the crucible with a little water, 
proceed as above. 

Jones Method.—This method is due to Prof. L. J. W. 
Jones,* and will be found extremely useful, especially where 
zinc for reduction which is free from arsenic and iron cannot 
be obtained. 

A hydrochloric acid solution of the ore is prepared in the 
usual manner. To this solution add about 20 grammes of 
test lead, and boil for from 5 to 8 minutes, according to the 
amount of iron present. The iron is reduced according to the 
equation 


Fe,Cl, + Pb = 2FeCl, + PbCl,, 
and may be determined by titration with standard potassium 
dichromate solution in the usual manner. The results are 


excellent. There are no interferences. Arsenic, antimony 
and copper which interfere with other methods are harmless. 


Proceedings Colo. Scientific Society, 1896. 


CHAPTER XVII. 


ALUMINIUM (Al). 


ONLY two methods are in general use for the determination 
of aluminium (Al) or alumina (Al,O,): Ist. Precipitation of 
the alumina as hydroxide with ammonia, filtration of the pre- 
cipitate, ignition to Al,O,, and weighing as such; 2d. Direct 
determination as aluminium phosphate (Al,P,O.). 

First Method.—This method presents the disadvantages 
common to all indirect methods, and is quite tedious, espe- 
cially in the case of a substance containing iron, phosphorus, 
chromium, titanium, etc. 

The method of procedure is as follows: The silica, and all 
metals of the sulphuretted-hydrogen group (As, Sb, Sn, Pb, Hg, 
Cu, Bi, and Cd), if present, must be removed from the solution. 
The silica is removed by any of the methods described in Part 
II, Chapter I. The metals of the sulphuretted-hydrogen group 
can be removed by passing a rapid current of sulphuretted- 
hydrogen gas through the filtrate from the silica, the precau- 
tion being observed that nitric acid is not present. After the 
sulphides are all precipitated, the solution should be rapidly 
filtered, and the beaker and precipitate on the filter should 
be thoroughly washed with distilled water, to which has been 
added some sulphuretted-hydrogen water. Should a precipi- 
tate of sulphides form in the filtrate, the solution should be 
again treated with sulphuretted-hydrogen gas until a precipitate 
no longerforms. The filtrate from the precipitated sulphides is 
heated to boiling, and the sulphur is oxidized by the addition 
of potassium chlorate or bromine-water, which should be added 


from time to time until the solution is perfectly clear. Should 
181 


182 A MANUAL OF PRACTICAL ASSA VYING. 


a precipitate form upon boiling (if much sulphuretted hydrogen 
was used yellow sulphur will separate), it should be filtered off. 
The solution is now ready for the precipitation of the 
aluminium as hydroxide with ammonia, which is effected as 
follows: Ammonia in slight excess is added to the solution, 
and the contents of the beaker are boiled until the free ammo. 
nia is driven off. This can be determined by holding a piece 
of glass, previously moistened with dilute hydrochloric acid, 
over the beaker; should no white fumes form the free ammonia 
has been expelled. It is essential that the free ammonia should | 
be expelled, as aluminium hydroxide is slightly soluble in an 
excess of ammonia. It is also essential that ammonium chlo- 
ride be present; sufficient will be formed when the ammonia is 
added if the solution contains much hydrochloric acid. The 
contents of the beaker are now ready for filtration, which is 
performed as usual, washing the precipitate thoroughly with 
hot water. Add a little ammonia to the filtrate, and boil. 
Should a precipitate form, filter it off, and add it to the first 
precipitate. This is essential, as when the amount of alumina 
present is large it may not all be precipitated the first time. 
The precipitate will consist of aluminium hydroxide, ferric 
hydroxide, if any iron was present in the solution (iron is gener- 
ally present); chromium hydroxide, provided chromium was 
present in the solution (except in the case of chromic iron ores 
and chrome iron and steel, chromium will rarely be encoun- 
tered); and also of phosphoric acid, which is present in all iron 
ores. The precipitate is now dried in an air-bath or by placing 
the funnel with the filter in a ring-stand over a sand-bath or 
hot plate. When dry the precipitate is transferred to a weighed 
platinum crucible by removing the filter from the funnei, 
inverting it over the crucible, and rolling it between the fingers. 
The filter is rolled into a bali, and placed upon the lid of the 
crucible, where it is burned and ignited over the flame of a 
burner. The contents of the lid are now added to the contents 
of the crucible, and the whole moistened with a few drops of 
nitric acid, the addition of nitric acid being necessary in order 
to oxidize any iron to the ferric form which might have been 


_-- - 


ALUMINIUM. 183 


reduced by the carbon of the filter-paper. A second addition 
of nitric acid, and a second ignition, is necessary where much 
iron is present and a large filter-paper has been used. The 
crucible and its contents are now ignited over the blast-lamp 
or in the muffle-furnace ai a bright-red heat, cooled, and 
weighed. The increase in weight of the crucible represents 
the weight of the combined alumina (AI,O,), ferric oxide 
(Fe,O,), phosphoric acid (P,O,), and chromic acid (Cr,O,). 

From the weight of the combined oxides calculate the 
percentage. From this percentage deduct the percentages of 
the different oxides, as determined, in separate portions. Ex. 
cept in the case of chromic titaniferous and phosphoric iron ores, 
the difference between the percentage of the combined oxides 
and the percentage of ferric oxide will be the percentage of 
alumina present. The percentage of ferric oxide present in the 
combined oxides may be determined as follows: Transfer the 
combined oxides, after weighing, to an agate mortar, and grind 
to an impalpable powder. Weigh out a portion of the powder, 
and fuse it with acid potassium sulphate in the manner de. 
scribed in Chapter I. Dissolve the fused mass in hot water, 
add an excess of sulphuric acid, reduce, and determine the 
iron as described in Chapter XVI. From the weight of the 
ferric oxide, as thus determined, calculate the total weight of 
the ferric oxide present in the combined oxides, and deduct 
it from the weight of the combined oxides, the difference 
being the weight of alumina in the amount of substance taken 
for analysis. When extreme accuracy is required the author 
prefers this method to the determination of the iron in a sepa- 
rate portion, and deducting that result from the weight of 
the combined oxides. 

Iron Ores.—Dissolve asin Chapter XVI. The treatment 
with sulphuretted hydrogen can usually b= omitted, as metals 
of the sulphuretted-hydrogen group are scldom present. To 
the filtrate from the silica add ammonia and proceed as above. 
When titanium and chromium are present they will be precipi- 
tated with the alumina. In this case proceed as described in 
Chapters XVIII and XIX, or by the second method. 


184 A MANUAL OF PRACTICAL ASSAYING, 


Manganese Ores.—Same treatment as with iron ores, ex- 
cept that it is necessary to dissolve the first precipitate of 
hydroxides with a little hydrochloric acid and reprecipitate 
with ammonia, in order to insure the separation of the man- 
ganese. 

Limestones, Clays, Cements, etc.—Same treatment as in the 
case of iron ores, taking the filtrate from the silica obtained 
as described in Chapter I. When a fusion of the insoluble 
residue has been necessary, combine the filtrates from the in- 
soluble and the silica. As the alumina is generally present as 
a silicate, it can be determined in these substances, with a 
sufficient degree of accuracy for technical purposes, as fol- 
lows: Determine the insoluble residue (see Chapter lI), and 
after weighing it fuse and determine the silica. The differ- 
ence between the weights of the insoluble residue and silica 
obtained will be the weight of alumina present. When barium 
is present the weight of the barium sulphate should also be 
determined and deducted from the weight of the insoluble 
residue. 

Silver and Lead Ores.—It will generally be sufficient to 
determine the insoluble residue (Chapter I) and the alumina 
by difference as in the case of clays. When the ore contains 
compounds of alumina which are soluble in acids, the filtrate 
from the silica, obtained by fusion, should be added to the 
filtrate from the insoluble residue, and the alumina determined 
in the combined solutions as above. In the case of lead ores 
which do not contain any members of the sulphuretted-hydro- 
gen group, except lead, the following method may be adopted: 
Determine the insoluble residue by treating with hydrochloric, 
nitric, and sulphuric acids and evaporation to fumes of sulphuric 
anhydride. The lead will all be converted into sulphate, and 
can be removed from the insoluble residue with ammonium 
acetate. The filtrate from the insoluble residue and lead sul- 
phate will now be free from lead, and the treatment with sul- 
phuretted hydrogen can be omitted. 

Slags, Mattes, etc-—Determine the alumina in the filtrate 
from the silica as above. In the case of lead and copper slags 


et 


ALUMINIUM. 185 


and mattes these metals will have to be removed by treatment 
with sulphuretted hydrogen. When much manganese or zinc 
is present, it will be necessary to redissolve the first precipitate 
of hydroxides in a little hydrochloric acid and reprecipitate 
with ammonia. If this precaution is omitted the results will 
be high, on account of the manganese and zinc carried down 
with the iron and alumina. A better method is to make a 
basic-acetate precipitation, dissolve the filtered and washed 
precipitate with a little hydrochloric acid, and reprecipitate 
with ammonia as above. 

Second Method.—This method, which was proposed by 
Dr. Drown,* depends upon the principle that if a slightly acid 
solution of aluminium and iron is electrolyzed with an anode 
of platinum and a mercury cathode, the iron will be precipi- 
tated on the mercury, and the solution, after precipitation of 
the iron, will contain all the aluminium, from which it (the Al) 
may be readily precipitated as a phosphate. This method is 
particularly adapted to the analysis of alloys containing com- 
paratively small quantities of aluminium and considerable iron. 
The method of procedure in the case of an iron or steel is as 
follows: Dissolve from 5 to 10 grammes of the substance in 
sulphuric acid, evaporate until white fumes of sulphuric 
anhydride appear, add water, heat to bring the iron into solu- 
tion, filter off the silica and carbon, and wash with water acid- 
ulated with sulphuric acid. Render the filtrate nearly neutral 
with ammonia, and add to the beaker, in which the electrolysis 
is to be made, about one hundred times as much mercury as 
the weight of iron or steel taken. The bulk of the solution 
should be from 300 to 500 cc. Connect with the battery or 
dynamo current so that about two amperes will pass through 
the solution over night. The connection with the mercury is 
dest made by means of a platinum wire fused into a piece of 
glass tubing which passes through the solution. The glass tube 
should be filled for about one inch with mercury in order to 


* Transactions of The American Institute of Mining Engir.eers Vol. XX, 
page 242. 


186 A MANUAL OF PRACTICAL ASSA VYING. 


weight it and make a perfect connection with the mercury ir 
the beaker., In the morning the solution is tested for iron, and 
if necessary the electrolysis is continued after adding sufficient 
ammonia to neutralize the acid set free by the deposition of 
the iron. The progress of the operation may be observed by 
the change in color of the solution. At first it becomes darker 
in color near the anode; after five or six hours it is nearly 
colorless, and finally becomes pink, from the formation of per- 
manganate. 

When the solution gives no reaction for iron, upon testing, 
it is removed from the beaker by means of a pipette while the 
current is still passing. When as much as possible has been 
removed without breaking the current, water is added and 
drawn off by the pipette as before. When the solution has 
been treated in this manner until there is no longer danger of 
resolution of the precipitated iron, the current is broken and 
the mercury is thoroughly washed with water until the last 
traces of the solution have been removed. Should the solutior 
not be perfectly clear, sometimes there will be a separation of 
oxide of manganese; it. should be filtered. The solution is now 
made nearly neutral with ammonia, sodium phosphate in excess, 
and about 10 grammes of sodium acetate are added, and the 
solution is boiled for at least forty minutes. The aluminium 
will be precipitated as a phosphate, which precipitate is filtered, 
washed, dried, ignited, and weighed. The ignited aluminium 
phosphate should be white. If it has more than the faintest. 
shade of color (due to iron), it should be fused with acid potas- 
sium sulphate, the fused mass being brought into solution with 
water and a little sulphuric acid, the solution finally being 
electrolyzed for 2 or 3 hours. The solution now free from iron. 
is drawn off and the aluminium is precipitated as a phosphate 
as before. This second precipitate will be pure. Drown states 
that he has generally found the first precipitate of such purity 
that this treatment and second precipitation are unnecessary. 
Drown states the ignited precipitate to have the composition 
7Al,O,, 6P,O,, in place of AlPO,, and consequently gives 24.14 
as the percentage of aluminium. 





ALUMINIUM. 187 


This method also answers for the determination of iron. 
If the iron is to be determined the mercury is weighed before 
proceeding with the electrolysis, and after electrolyzing wash- 
ing and decanting, it is dried for a few minutes at a tempera- 
ture of 100° to 110° ©. and weighed again. The increase in 
weight of the mercury represents the weight of iron in the 
amount of substance taken. As mercury loses weight upon 
drying, even at such a low temperature as 100°C., and there 
is generally a loss in weight owing to the impurities in the 
mercury which pass into solution, it is best to run a blank 
beaker, containing about the same weight of mercury as is 
used in the analysis, and water slightly acidulated with sul- 
phuric acid, in the circuit with the analyses. The loss in 
weight of the mercury used in the blank should be added to 
the results in the case of each iron determination. 

This method may also be used for the determination of 
iron and aluminium in ores, etc. 


CHAPTER XVIII. 


CHROMIUM (Cr). 


CHROMIUM is always determined as chromic oxide (Cr,O,), 
dark green in color. 

The only determinations of chromium which the metallur- 
gical chemist will be called upon to make are in iron ores 
(especially chromic iron ore, known as chromite, or mag- 
netite, which sometimes contain chromium), pig-iron, and steel. 

Ores.—F use from I.0 to 2.0 grammes of ore with 5 to Io 
grammes of mixed carbonates of sodium and potassium and 
I gramme of sodium nitrate (see Part II, Chapter 1). Dissolve 
the fused mass in water and hydrochloric acid in slight excess, 
evaporate to dryness, and determine the silica in the usual way. 
To the filtrate from the silica add sodium carbonate until it 
is strongly alkaline, and then, without filtering out the precipi- 
tate, bromine water until the solution is deeply colored, stirring 
continually. Now add 3 cc. of pure bromine and heat for one 
hour, with frequent stirring, keeping the solution alkaline and 
sradually increasing the heat until it boils. Allow to boil for an 
hour, when the chromic oxide should all be oxidized to chromic 
acid. Now filter (precipitate A) and wash thoroughly with hot 
water, washing first by decantation and then on the filter until 
tie filtrate runs through colorless. Should the ore contain a 
large amount of chromium, in order to insure its complete sepa- 
ration, wash the precipitate on the filter back into the beaker 
with the wash-bottle, bring the bulk of the solution up to about 
100 cc. with water, add 2 cc. of bromine, and proceed as before, 
filtering through the same filter. The filtrate will now contain 


all of the chromium as alkaline chromate, and probably some 
s 188 


CHROMIUM. 189 


of the manganese. The precipitate will contain all of the 
other constituents of the ore. Partially neutralize the filtrate 
with nitric acid, add from I to 3 grammes of ammonium 
nitrate, and evaporate until no odor of ammonia is perceptible. 
Dilute with water, and should a precipitate form (precipitate B, 
probably MnO,, SiO,, Al,O,, and TiO,), filter, and wash with 
warm water. Acidify the filtrate with hydrochloric acid, and 
saturate it with sulphuretted hydrogen to reduce the chromic 
acid to sesquioxide. Filter out the precipitated sulphur and 
wash. In the filtrate precipitate the chromic hydroxide with 
ammonia, filter, wash, dry, ignite, and weigh the chromic 
oxide (Cr,O,). To obtain the weight of the chromium multiply 
the weight of the precipitate by 0.68586. 

Pig-iron, Steel, etc.—Dissolve the alloy in nitric and 
hydrochloric acids, evaporate to dryness, dry, and ignite the 
insoluble residue. Fuse the insoluble residue with mixed car- 
bonates and proceed as above. 

Titaniferous Ores containing Chromium.—Proceed as 
described in Part II, Chapter XIX (Titanium), for the deter- 
mination of the silica. Treat the filtrate from the silica as 
described above for the determination of the chromium. For 
the determination of the iron and titanium combine precipitate 
B (should one form) with the sodium-carbonate precipitate A. 
Dissolve the combined precipitates in hydrochloric acid, and 
proceed to determine the titanium as described in Chapter 
x1 £11), 

Determine the iron in the filtrate as described in Chapter 
XIX (Ti) and Chapter XVI (Fe). 


CHAPTER XIX. 


TITANIUM (Ti). 


TITANIUM is generally determined by the gravimecric 
method as titanic oxide, but may also be determined by the 
colorimetric method. 

About the only determinations of titanium which the metal- 
lurgical chemist will be called upon to make are the determina- 
tions in iron ores (especially some magnetites), in pig-iron, and 
occasionally steel. 

When titanium is present the method of determining the 
iron and silica in iron ores, pig-iron, etc., will have to be modi- 
fied, and the titanium first separated according to the gravi- 
metric method described below. 

Colorimetric Method.—This method is due to Weller,* 
and the improvements to H. L. Wells ¢ and W. A. Noyes.{ 

Mix 0.1 gramme of ore with 0.2 gramme of sodium fluoride, 
both finely powdered, in a platinum crucible. Add 3 grammes 
of sodium pyrosulphate without mixing. Fuse carefully and 
heat gently until the effervescence ceases and copious fumes 
of sulphuric acid are evolved. This should take two to 
three minutes. When cold the mass in the crucible is dissolved 
in from 15 to 20 cc. of cold water, and the solution filtered and 
washed slightly. If a residue remains it can be treated again 
by the same method after burning it on the filter, but the 
amount of titanium usually found by a second fusion is small. 

To the solution, as obtained above, 1 cc. of hydrogen per- 





* Berichte d. Chem. Ges., 1882, p. 2592. 
+ Trans. Am. Inst. .of Mining Engineers, Vol. XIV, p. 763. 
¢ Journal of Analytical and Applied Chemistry, Jan. 1891. 
190 


TITANIUM. 19! 


oxide and a few cc. of dilute sulphuric acid are added, when 
the solution is ready for comparison with a solution containing 
a known amount of titanium. Fora standard solution titanic 
oxide is dissolved in hot concentrated sulphuric acid, and the 
solution diluted with dilute sulphuric acid at first (to prevent 
the precipitation of titanic oxide), and then with water until 
I cubic centimetre contains 1 milligramme of TiO,,. 

As iron affects the color of the solution, ferric sulphate, 
approximately in the same proportion as iron is present in the 
ore, should be added to the standard solution. A solution of 
iron-ammonium alum answers well for this purpose, and, if the 
amount of iron in the ore is not known, all that is necessary is 
to match the color of the solution of the mineral before adding 
the hydrogen peroxide to it. Small quantities of titanium in 
the presence of large quantities of iron can be readily deter- 
mined by this method, which is especially adapted for technical 
determinations. 

Gravimetric Method.—For the technical estimation of 
titanium in iron ores, pig-iron, etc., the following method is as 
rapid and accurate as any: * 

Iron Ores.—Fuse 1.0 gramme of finely pulverized ore with 
IO grammes of pure potassium bisulphate in a large platinum 
crucible, heating the covered crucible over a very low flame 
until the bisulphate is melted. This operation must be care- 
fully conducted, as there is danger of the bisulphate boiling 
over, and also loss from spirting. Raise the heat very gradu- 
ally, keeping the mass just liquid and the temperature at the 
point at which slight fumes of sulphuric anhydride are given 
off when the lid is slightly raised, until the bottom of the cru- 
ible is dull red. When the ore is completely decomposed, 
remove the heat, take off the crucible lid, and incline the 
crucible at such an angle that the fused mass will run together 
on one side of the crucible and as near the top as possible. 
Allow it to cool in this position; when cold it is easily de- 
tached from the crucible. Place the crucible and lid in a 
beaker (No. 4) half full of cold water, and the fused mass in a 


‘* Blair’s ‘‘ Chemical Analysis of Iron.”” Tenth Census U. S., Vol. XV, p. 512. 


192 A MANUAL OF PRACTICAL ASSA YING. 


small platinum tray or basket suspended in the beaker. Pour 
into the beaker sufficient strong aqueous solution of sulphur- 
ous acid to raise the liquid to the top of the basket, and allow 
the fusion to dissolve, which may require twelve hours. Re- 
move the crucible, lid, and basket, washing off with a jet of 
cold water. Stir the solution, which should smell strongly of 
sulphurous acid, and allow the insoluble matter to settle. Filter, 
wash, dry, ignite, and weigh the insoluble residue. Treat with 
hydrofluoric acid and a few drops of sulphuric acid, evaporate 
to dtyness, ignite, and weigh, the loss being silica. Should 
any appreciable residue remain, fuse it with sodium carbonate, 
dissolve the fusion in water and sulphuric acid, heat, and add 
to the main filtrate. To the combined solutions, which should 
be colorless and smell strongly of sulphurous acid, add a clear 
filtered solution of sodium acetate (20 gms.) and one sixth its 
volume of acetic acid (1.04 sp. gr.), heat to boiling, and con- 
tinue to boil for a few minutes. Allow to settle, filter on an 
ashless filter; wash thoroughly with hot water containing 17 
per cent acetic acid, and finally with hot water; dry, ignite, and 
weigh as TiO,. This precipitate is seldom quite pure, as it is 
liable to contain small amounts of Fe,O, and Al,O,. Hence it 
is best to fuse it with sodium carbonate, dissolve in water, 
filter, wash, dry, and fuse the insoluble sodium titanate with 
sodium carbonate, dissolving the fusion, when cool, in the 
crucible with sulphuric acid, and precipitate and determine 
the TiO, as above. 

To obtain the weight of titanium, multiply the weight of 
the titanic oxide found by 0.60976. 

Pig Iron, ett.—Decompose according to Drown’s method 
for the determination of silicon (Part I, Chapter I, page 85), 
dry, and ignite the residue of silica, graphite, etc. Treat this 
residue with hydrofluoric acid and sulphuric acid to expel 
silica and evaporate the fumes of sulphuric anhydride. Finally, 
evaporate to dryness and fuse with sodium carbonate. Dis- 
solve the fusion in water and sulphuric acid, heat, and add the 
solution to the main filtrate. Proceed with this solution as 
with iron ores. 


we, 


a ig ie ae 


TITANIUM. 193 


Slags.—Treat 2 gms. of finely pulverized slag in a large 
platinum crucible with an excess of hydrofluoric acid and 5 cc. 
of conc. sulphuric acid. Evaporate off the hydrofluoric acid, 
and heat carefully until the greater part of the sulphuric acid 
is driven off. Allow the crucible to cool, add Io gms. of 
sodium carbonate, fuse for half an hour, finally at a high heat, 
and remove the crucible, running the fused mass well up on 
its walls. Dissolve the fused mass in water, transfer to a 
beaker, and filter. Wash the insoluble matter, dry, ignite, and 
re-fuse it with sodium carbonate. Dissolve in water as before, 
and filter. By this method alumina will be entirely separated 
from the titanium. Fuse the insoluble matter on the filter 
with sodium carbonate, dissolve the fusion, when cool, with 
sulphuric acid, and determine the titanium as above. 


CHAPTERS Xx 


MANGANESE (Mn). 


A NUMBER of methods for the determination of manganese 
have been proposed, and a number of different methods are in 
use. There seems to be considerable difference of opinion 
between many of our best chemists as to which are the best 
methods. However, the methods described below are all in 
use in some of our largest metallurgical works and by some of 
our most reliable technical and commercial chemists. 

Ford’s Method.*—This method was first proposed for the 
determination of manganese in spiegels, irons, and steels, but 
is applicable to slag, ores, etc., if slightly modified. From 0.5 
to 2.0 grammes of substance, depending on the percentage of 
manganese it contains, are dissolved in from 25 to 50 cc. of 
strong nitric acid (1.4 sp. gr.) perfectly free from chlorine. 
Evaporation to dryness is not necessary, except where the 
amount of silicon is large, as in the case of certain pig-irons. 
Then, as a clogging of the filter in the subsequent filtration is 
apt to follow, dissolve first in a dish in hydrochloric acid, using 
as small an amount of acid as possible, and quickly evaporate 
to dryness. Take up with nitric acid and evaporate again to 
dryness. This second evaporation is necessary in order to 
remove all the hydrochloric acid, which, if present, would 
interfere with the subsequent precipitation of the manganese. 
Slag, ores, and such other material as contains much silica, 
should also be treated in this way. Redissolve for the second 


* Transactions of the American Institute of Mining Engineers, Vol. IX, 


p. 397- 
104 


MANGANESE. 195 


time in- strong nitric acid, and boil until the red fumes cease 
coming off, and while boiling throw in crystals of potassium 
chlorate from time to time. Violent action ensues, yellow 
fumes are driven off, and binoxide of manganese is precipi- 
tated, since it is insoluble in strong nitric acid. As soon as 
all of the manganese has been oxidized the fumes will cease 
coming off, with a slight explosion. After this has occurred, 
add a few more crystals of potassium chlorate, boil for a min- 
ute or two, remove from the lamp, and filter through an 
asbestos filter. The most convenient apparatus is a small 
funnel-shaped tube in which is fitted an asbestos plug, the 
filter-pump being used to facilitate filtration. The asbestos 
should be free from soluble lime, magnesia, and manganese. 
It is best to prepare it by treating it successively with boiling 
hydrochloric acid, boiling water, boiling nitric acid, and then 
boiling water until the washings no longer show a trace of 
these elements when treated with the proper reagents. The 
asbestos should then be ignited to free it from organic matter. 
This is of the utmost importance, as the writer has known of 
more than one chemist who condemned this method as giving 
too high results, when upon investigation it was found that 
they had not taken the precaution to purify the asbestos used, 
which probably accounted for the high results obtained. 

After filtering the nitric-acid solution through the asbestos 
filter, rinse the dish or beaker in which the substance was dis- 
solved with strong nitric acid, pour it upon the filter, and wash 
with strong nitric acid until the washings come through color- 
less. The funnel-tube is then removed from the filtering ap- 
paratus, the filter with its contents placed back into the dish 
in which the solution was made, hydrochloric acid added, and 
the substance boiled until the manganese binoxide is dissolved 
as chloride. The asbestos is then removed by filtration, using 
the same tube and filter-pump, and finally washing with hot 
water. Nearly neutralize the filtrate with ammonia, adding a 
few crystals of sodium acetate, and boil, filter, wash slightly 
with hot water, redissolve the small precipitate of iron oxide 
in hydrochloric acid, again nearly neutralize with ammonia, add. 


196 A MANUAL OF PRACTICAL ASSA YING. 


a crystal or so of sodium acetate, boil, and filter. The solution 
and reprecipitation of the iron is necessary as a small amount 
of manganese is always contained in the first precipitate. Add 
the second filtrate to the first, heat nearly to boiling, and add an 
excess of microcosmic salt. Then make slightly ammoniacal, 
and boil, stirring until the precipitate assumes the characteris- 
tic appearance of the phosphate of ammonia and manganese. 
Allow it to settle, and filter, wash with hot water, dry, ignite, 
and weigh as pyrophosphate of manganese. 

It is best to use some filter-paper which is pure, such as 
Schleicher & Schuell’s c. p., for both filtrations, as many of 
the qualitative papers contain appreciable quantities of man- 
ganese. . 

In the case of slags or other substances containing lime 
and magnesia, it is necessary to wash the binoxide precipitate 
more thoroughly with nitric acid in order to remove all of 
these elements. 

Evaporation to dryness in the case of steels or spiegels is 
not necessary. They may be immediately dissolved in strong 
nitric acid, and potassium chlorate added. A determination 
may be made in two hours by this method. 

Williams’s Method.*—Mr. H. Williams has proposed a 
modification of the above method which shortens it somewhat, 
and simplifies it, especially in the case of a substance which 
contains lime or magnesia, as, for example, slag. 

The substance is treated, as before, with nitric acid, and 
potassium chlorate (in the case of a pig-iron, slag, etc., the 
silica and carbon must first be removed by filtration through 
asbestos) added to precipitate the manganese. After filtering 
off this precipitated manganese binoxide, wash with strong 
nitric acid, and then well with water. Blow the contents of 
the funnel into the beaker in which the precipitation was 
made, which should previously be well washed, and rinse the 
funnel with a little water. 


* Transactions of the American Institute of Mining Engineers, Vol. X, 
p. TOO. 


MANGANESE. IQ7 


Run into the beaker an accurately measured quantity of a 
standard solution of oxalic acid (a moderate excess over what 
the manganese binoxide is capable of oxidizing), add water to 
bring the bulk of the solution up to about 75 cc., and then 3 or 
4 cc. of concentrated sulphuric acid, and heat to about 70°C, 
The solution of the binoxide is readily effected by the aid of a 
little stirring. Finally, titrate the solution with a standard so- 
lution of potassium permanganate. (See Part II, Chapter XVI.) 
The presence of the asbestos does not obscure the final reac- 
tion. Two standard solutions are necessary, viz., a permanga- 
nate solution and an oxalic solution. 

It is best to use a decinormal permanganate solution, i.e., 
I cubic centimetre equal to 1 milligramme of iron. By using 
such a dilute solution the accuracy of the method is greatly 
increased. The permanganate solution may be prepared by 
dissolving 1.2 grammes of potassium permanganate in 2030 
cc. of distilled water. It should be prepared and standardized 
as described in Part II, Chapter XVI. 

The oxalic solution may be of almost any strength, but if 
it is made so that 1 cc. will require about 3 cc. of the perman- 
ganate solution to oxidize it, it will answer well. It should be 
kept in a tight-stoppered bottle in a dark place, and should 
be standardized from to time with the standard permanganate 
solution. 

The method of calculating the result is best shown by the 
following example: Suppose we have taken I gramme of steel, 
in which we suspect about I per cent of manganese. Having 
separated the binoxide, we add 15 cc. of the standard oxalic- 
acid solution of the strength already mentioned, and effect the 
the solution as described. This 15 cc., by itself, would require 
45 cc. of the permanganate, but on titrating we use, say, 25 cc.; 
the difference, 20 cc., is equivalent to 0.020 gramme of iron. 
Since 1 equivalent of manganese binoxide converts 2 equiva- 
lents of a proto-salt of iron to the state of a sesqui-salt, as 
shown by the formula 


2FeSO, + MnO, + 2H,SO, = Fe,(SO,), + MnSO, + 2H,0, 


198 A MANUAL OF PRACTICAL ASSAYING. 


the solving of the proportion 112: 55 ::0.020: 4 gives the 
weight of the manganese equivalent to the 0.020 gramme of 
iron. The value of x is 0.00982 and the per cent is 0.982. It 
will be seen from the above that in operating on ores or prod- 
ucts which contain a high percentage of manganese it will be 
necessary to take smaller quantities of the substance. 

Sometimes when the percentage of manganese is high it 
may be advantageous to use a stronger solution of oxalic acid 
and also a stronger solution of permanganate,—say a half- 
normal solution. 

The results obtained by this method agree very closely be- 
tween themselves, and also with the results obtained by Ford’s 
method. 

The following modification of Ford’s method the writer has 
used for the determination of manganese in ores and slags with 
very good results: Dissolve the precipitated binoxide with 
just sufficient hydrochloric acid to cause the precipitate to go 
into solution, and add a little sulphuric acid. An emulsion of 
pure zinc oxide is now added, a little at a time, shaking or 
stirring the solution until the hydrochloric acid is neutralized 
and the zinc oxide is in slight excess. Care should be exer- 
cised not to add too large an excess of zinc oxide, as if too 
large an excess is present it will obscure the reaction, and fil-. 
tration will be necessary before the solution can be titrated. 
The solution is now ready for titration with standardized per- 
manganate solution in the manner described under the head of 
Volhard’s Method. 

Volhard’s Volumetric Method.—This method, which is 
generally used in the Western lead, and copper-smelting works, 
may be used for the determination of manganese in iron, man- 
ganese, lead, copper, silver, and gold ores, etc., and also for the 
determination of manganese in other substances, such as spiegel, 
steel, etc. 

Dissolve 1 gramme of substance in 2 cc. of hydrochloric, 
4 cc. of nitric, and 6 cc. of dilute sulphuric acids in a flask or 
casserole, as in the determination of iron, and evaporate to 
copious fumes of sulphuricanhydride. Transfer the contents of 





MANGANESE. 199 


the flask or casserole to a graduated 500-cc. flask, washing into 
the flask with boiling water. Then add an emulsion of zinc 
oxide to the contents of the flask until the acid is neutralized 
and the iron is all precipitated as sesquioxide, violent shaking 
of the contents of the flask facilitating the precipitation of the 
irons Atter the precipitation is complete the oxide of zinc 
should be in slight excess. The contents of the flask are then 
diluted with distilled water to the holding mark, and after 
thorough shaking allowed to settle. After the oxides have 
settled so that the supernatant liquid is comparatively clear, 
100 cc. is drawn off by means of a pipette and transferred toa 
flask (about 250 cc. capacity), rinsing out the pipette with dis- 
tilled water into the flask. The contents of the small flask are 
then brought to a boil by heating over a flame, and are then 
ready for titration with a standard solution of permanganate 
of potassium. The titration is performed as follows: The per- 
manganate solution is dropped into the liquid in the flask from 
a burette, the contents of the flask being shaken after each ad- 
dition of permanganate solution in order to facilitate the set- 
tling of the precipitated manganese dioxide. From the amount 
of the precipitate and the rapidity with which the precipitate 
is formed after each addition of permanganate solution, the 
operator after a little practice will be able to determine in 
what quantities it is safe to add the permanganate solution. 
The addition of permanganate should be continued until a 
faint pink color appears around the edges of the clear liquid 
after shaking, when held against a white background. The 
precipitation of the manganese is then complete, although it is 
safest, especially if the precipitation has occupied some time, to 
bring the contents of the flask again to a boil, and notice, after 
allowing the precipitate to settle, if the pink tint remains. If 
the color should have disappeared another drop of permanga- 
nate is added, the flask shaken, and the precipitate allowed to 
settle. If the color is permanent after settling the titration is 
completed. 

The same solution of potassium permanganate used for the 
determination of iron may be used for this determination. In 


200 A MANUAL OF PRACTICAL ASSAYING. 


order to determine how much manganese one cubic centimetre 
of the permanganate solution is equal to, it is only necessary 
to multiply its value for iron. by 0.2946 to obtain its value for 
manganese. Hence if the 1 cc. of the permanganate solution 
was equal to 0.010 gramme of iron, it would be equal to 
0.002946 gramme of manganese. The reaction which takes 
place is as follows: 3MnO ++ Mn,O, = 5MnO,,. 

Many chemists prefer to filter off the precipitatea oxides 
before diluting to 500 cc.; but this is unnecessary, as the pre- 
cipitate occupies such a small bulk, although in the flocculent 
state its bulk appears to be large, that it may be disregarded. 
Moreover, the precipitate is difficult to wash, and filtration 
generally gives low results. The method gives closely agree- 
ing results, and results which are as good as if not better than 
those obtained by the other methods with the same degree 
of proficiency in practice. The zinc oxide should be tested, 
and, if it contains manganese or organic matter, purified. If 
commercial zinc is used it will be necessary to purify it. 

Colorimetric Method.—This method was first used in 
this country by Mr. Samuel Peters,* and is especially appli- 
cable to the estimation of manganese in steels, and such 
substances as contain less than 1$ to 2 per cent of manganese. 
The method, as used in iron and steel laboratories, is essentially 
as follows, for steels: Dissolve 0.1 gramme of the steel in 20 
cc. nitric acid (1.20 sp. gr.) in a test-tube about nine inches 
long by one inch in diameter, by the aid of heat, boiling the 
solution until the carbonaceous matter is entirely in solution 
and all nitrous fumes are evolved. This usually takes about 
five minutes at a gentle ebullition. Then add, with a platinum 
spatula, about 0.4 gramme of pure peroxide of lead to the 
boiling solution, adding first a small portion of the lead, and 
as soon as the violent action ceases, an instant later, the 
remainder of the salt, boiling gently but continuously for 
exactly two and a half minutes longer, then removing from 





* Crooks’ Select Methods. Transactions of the American Institute of Mining 
Engineers, Vol. XV, p. 104. 


te emote) alin te i 


MANGANESE. 201 


the heat, and placing the test-tube in a beaker of cold water, 
out of contact with the direct rays of sunlight, and allowing 
the solution to cool and to settle for about an hour. The 
clear supernatant solution is then ready to decant off from the 
lead into the graduated tube, and to match, by dilution with 
distilled water, with the standard solution containing 0.0001 
gramme of manganese as permanganate in each cc. of solu- 
tion; so that, using 0.1 gramme of steel for the analysis, each 
cc. of the solution to be determined will represent o.o1 per 
cent of manganese when the shades of color match. 

The standard solution for comparison may be made in 
several ways, but the best are to use either a standard solution 


of potassium permanganate or, preferably, the standard may 


be prepared by using 0.1 gramme of a standard steel contain- 
ing a known percentage of manganese, treating it exactly as 
the unknown sample, and decanting the solution into a simi- 
larly graduated tube, and diluting with water until the solution 
has a volume of which the number of cc. is an equivalent or 
multiple of the percentage of manganese in the steel, applying 
the same principle as is used with the standard steels in the 
Eggertz method for the estimation of carbon (see Part II, 
Chapter IV). This method is preferable to the other methods 
of making a comparison, and it is also preferable to run a 
standard with each set of analyses. 

A. E. Hunt* says: “ This method, when properly used, is 
at least sufficiently accurate for all practicable purposes within, 
say, 0.02 per cent manganese for steels within the range of from 
0.15 to 1.50 per cent manganese. It is fully as accurate, and 
can be as safely guarded from error, as the Eggertz color-method 
for the estimation of carbon in steel.” The method, however, 
has many sources of error that must be carefully avoided. 

Mr. Hunt recommends the following precautions : 

First. The drillings of steel must have no oil or other 
extraneous matter with them. Owing to the ease with which 


._ *Transactions of the American Institute of Mining Engineers, Vol. XV, 
Pp. 106. 


# 


202 A MANUAL OF PRACTICAL ASSA YING. 


permanganate solutions are reduced, it is necessary that no 
‘organic matter be present which will not be entirely destroyed 
by the boiling nitric acid before the addition of the peroxide 
of lead. 

Second. The nitric acid must be pure, and especially free 
from chlorine or nitrous fumes. The acid must be of very 
nearly 1.20 sp. gr. throughout the process. and must not be al- 
lowed to become much more concentrated by boiling. It is 
best to cover the mouths of the test-tubes with clean covers 
of porcelain crucibles during the ebullition. If the acid be- 
comes too concentrated during the boiling, as it is very liable 
to do if the ebullition becomes too violent and the test-tube is 


a large one, on the addition of the peroxide of lead some of . 


the manganese is transformed into the insoluble manganese 
binoxide and precipitated. 

Third. The peroxide of lead must be free from color on 
boiling with the dilute nitric acid, and must be so free from 
lead nitrate that it will oxidize all the manganese in the steel 
into a reasonably permanent permanganic acid. This is avery 
important point, which, not properly guarded, has occasioned 
failures, and has caused many chemists to condemn the method. 
In commencing the use of any new lot of peroxide of lead 
it is a necessary precaution to mix up the salt thoroughly 
and then to test it by making an analysis with a steel of known 
composition, comparing it with a standard solution of potassium 
permanganate, and obtaining a concordant result. Most of the 
peroxide of lead found in the markets and sold as c. p. is non- 
homogeneous, and contains considerable quantities of nitrate 
disseminated through it. It is best to purify your own perox- 
ide of lead. | 

Fourth. The ebullition must not be too violent, and must 
not last over two and one half minutes. It is necessary to 
stand by the tubes with watch in hand and to remove them 
when the time is up. Too long boiling invariably gives bad 
results. The boiling is best done in a water-bath in which 
chloriae of calcium is added to the water to raise its boiling- 
point. 


vs. 


MANGANESE. 203 


Fifth. There must not be hydrochloric acid, sulphuretted 
hydrogen, or other fumes in the air of the room in which the 
tubes are allowed to stand to cool. Itis best not to allow the 
solution to stand too long—never two hours—before com- 
parison. 

Sixth. Mr. Hunt says: “I have had no trouble in getting 
good, reasonably permanent colors, but have never had _ uni- 
formly satisfactory results by filtering the solution from the 
peroxides through asbestos, and have consequently preferred 
to decant off the solution from the lead. When a standard 
steel is used, having nearly the same percentage of manganese 
as the sample to be determined, equal amounts of solution and 
treatment exactly the same so far as practicable, the error due 
to the amount of the liquid remaining with the lead in the bot- 
tom of the tube is comparatively trifling, never over 0.02 per 
cent, when the precautions mentioned above are carefully ob- 
served.” 

Seventh. The water used in diluting must be free from 
organic matter. The ordinary distilled water used in chemi- 
cal laboratories often contains considerable organic matter, 
which will rapidly reduce the permanganate solution. 

Eighth. The mixing of the color solutions for comparison 
can best be done by having the graduated tube provided with 
a glass stop-cock, or it can be satisfactorily performed by pour- 
ing the solution out into a clean beaker and then decanting 
back into the graduated tube. 

This method is especially applicable, owing to its simplic- 
ity and rapidity, for checking and controlling the converting 
and mill work in a steel-works. When great rapidity is neces- 
sary, as it sometimes may be in this latter case, the solution 
need not be allowed to stand so long after the addition of the 
peroxide of lead, but may be filtered through asbestos, using 
the filter-pump. | 

The above methods will serve for the estimation of man- 
ganese in almost. any substance. Volhard’s method is the one 
generally used in the West, and is the simplest and most rapid. 
In the case of oxidized ores, soluble in hydrochloric acid, the 


204 A MANUAL OF PRACTICAL ASSA YING. 


addition of nitric and sulphuric acids may be dispensed with, 
the ore being dissolved directly in a small quantity of hydro- 
chloric acid, and the manganese determined by Volhard’s 
method as above. In the case of slags, when the sample has 
been suddenly chilled (Chapter I), treat with water and hydro- 
chloric acid, as in the determination of silica, add a few crystals 
of potassium chlorate, heat to oxidize the iron, etc., and deter- 
mine by Volhard’s method. When the sample has not been 
suddenly chilled, make a cintering fusion (Chapter I), dissolve 
fused mass as above, evaporate to dryness and heat. Redis- 
solve in hydrochloric acid, and proceed by Volhard’s method. 

Mr. A. H. Low* proposes a method for the determination 
of manganese in ores which is a combination of Volhard’s and 
William’s methods, and which is said to give excellent results. 

The method is essentially as follows; Dissolve 0.5 gm. of 
ore in hydrochloric acid, or nitrohydrochloric acids, in a flask. 
Heat until most of the free acid is expelled, dilute with 75 cc. 
of water, add an excess of zinc oxide, and boil. Now add a 
saturated solution of bromine-water (not over 50 cc.), and boil 
out the excess of bromine. The sclution should still contain 
an excess of zinc oxide. Filter, and wash the precipitate thor- 
oughly with hot water. Return the washed precipitate to the 
flask and add 50 cc. of dilute sulphuric acid (1 ing). Warm 
to dissolve the iron, and run inan excess of oxalic-acid solution 
from a burette, heat, dilute with warm water, and titrate the 
excess of oxalic acid with a standard solution of potassium 
permanganate. 

The permanganate solution should be about one-tenth nor- 
mal. The oxalic-acid solution is prepared by dissolving 11.46 
ems. of pure crystallized oxalic acid in 1000 cc. of water. The 
solutions are standardized in the usual manner, and their rela- 
tions to each other determined. 


* Journal of Analytical and Applied Chemistry, Vol. VI, p. 663. 


CHAPTER XXI. 


ZINC (Zn). 


SEVERAL methods have been proposed for the determination 
of zinc both gravimetrically and volumetrically. Only one, 
the volumetric estimation by a standard solution of potassium 
ferrocyanide, will be given. For the standard gravimetric 
methods see Fresenius, Cairns, Rose, etc. 

This method, provided the proper precautions are used, 
gives results which agree as closely with the results obtained by 
any of the standard gravimetric methods as two gravimetric 
determinations of the same sample will agree among them- 
selves, provided the percentage of zinc present is not very low 
(less than 4 per cent). The accuracy of the method has been 
fully demonstrated. See Proceedings of the Colorado Scien- 
tific Society, June 1892, and The School of Mines Quarterly, 
Vol XIV, No. 1, p. 40. 

It is the opinion of the writer, after numerous experiments, 
that once the zinc is obtained in solution in the proper form 
its percentage may be more safely determined by this titra- 
tion method than it can be by precipitation and subsequent 
ignition and weighing. It, moreover, has the advantage of 
being rapid, and consequently would be used in metallurgical 
works in many instances, even if the results were not quite up 
to the standard of accuracy. 

This method requires a standard solution of potassium 
ferrocyanide. A solution of which one cubic centimetre is 
equal to 0.010 gramme of zinc is the solution generally pre- 
ferred by most chemists using this method. To prepare such 
a solution 90 grammes of pure potassium ferrocyanide (free from 

205 


206 A MANUAL OF PRACTICAL ASSAYING. 


potassium ferricyanide) are dissolved in two litres of water and 
kept in a tightly-stoppered green-glass bottle. _The solution 
will keep for some time without alteration, provided the bottle 
is well stoppered, and need not be tested more frequently than 
once every two or three weeks. It is best to make up the solu- 
tion at least one day before using. To standardize the solution, 
dissolve two portions of about 0.250 gramme each of pure zinc 
oxide (the zinc oxide should previously be ignited to convert 
any carbonate of zinc into oxide, and kept in a stoppered 
bottle so that it may not absorb carbonic acid or water from the 
air) in 5 cc. of pure hydrochloric acid, and add 50 cc. of water 
in a beaker of about 300 cc. capacity. In order to have the 
same conditions present as near as possible as in the actual 
analysis, it is well to add ammonia in slight excess and then 
neutralize with hydrochloric acid, using asmall piece of litmus- 
paper as an indicator. When the solution has been brought 
to the point where it is just slightly acid, add an excess of 10 cc. 
of pure strong hydrochloric acid, and dilute to 250 cc. with 
cold distilled water. The solution is now ready for titration 
with the ferrocyanide solution, which may be run in from a 
burette, rapidly at first, stirring from time to time. If 0.2493 
gramme of pure oxide of zinc were weighed out, it would require 
just 19.99 cc. or practically 20 cc. of the ferrocyanide solution to 
precipitate the zinc, provided the solution was normal; hence 
in this case about 18 cc. may be run in before testing. In 
order to test, the solution is thoroughly stirred with a glass rod, 
and a drop removed and added to a drop of a solution of pure 
uranium acetate on a porcelain plate. The uranium-acetate 
solution is prepared by dissolving sufficient uranium acetate in 
water to give a pretty strong solution, and clarified by adding 
a few drops of acetic acid. This solution should be kept in a 
small stoppered bottle in a dark place, as it is decomposed by 
the action of sunlight. As long as there is not an excess of fer- 
rocyanide in the solution the drop of uranium acetate will retain 
its yellow color; as soon as the ferrocyanide is in slight excess 
it will turn a light brown, the shade being darker according to 
the amount of ferrocyanide in excess. The titration should be 


ZINC. 207, 


proceeded with, testing after the addition of each drop of 
ferrocyanide towards the last of the operation, and stirring well 
before testing, until a slight brownish tint is produced on the 
drop of uranium acetate. The amount of ferrocyanide used is 
then noted, and the value of one cubic centimetre calculated. 
The duplicates should not differ by more than one tenth of a 
cubic centimetre. 

The precautions to be observed are: to have about the same 
bulk of solution in all subsequent titrations; to have the same 
amount of hydrochloric acid present; to have the standard 
solution at about the same temperature, and to have the zinc 
solution comparatively cool. If too large an excess of acid is 
present, orif the zinc solution is too warm, a decomposition will 
ensue, resulting in the liberation of chlorine. This may be 
seen by the solution turning yellow or a yellowish green. The 
precipitate should always be white, and the solution colorless 
or nearly so. This method is due to Fahlberg. 

To determine the zinc in an ore by this method, the zinc 
solution must first be freed from such elements as copper, iron, 
manganese, etc., which are also precipitated in an acid solution 
with the ferrocyanide, or react on it. The three elements 
named above are the ones most likely to be encountered in 
zinc-ores. Should cadmium be present (its presence in ores of 
zinc is rare) it: must be removed before proceeding with the 
titration. 

The following method will serve for the determination of 
zinc in all ores and furnace-products, except in the special cases 
mentioned below. 

Method of Von Schulz and Low modified.*—Treat 1 
gm. of finely pulverized ore with 15 cc. of aqua regia, and 
evaporate nearly to dryness. Should the ore be incompletely 
decomposed, which will seldom happen, evaporation to dryness, 
dehydration of the silicic acid, and fusion of the insoluble res- 





* The Mining Industry, Denver, Colo., Vol. VI, No. 13; Proceedings of 
the Colorado Scientific Society, June 1892; School of Mines Quarterly, Vol. 
XIV, No. 1. 


208 A MANUAL OF PRACTICAL ASSA YING. 


idue with carbonate and nitrate of soda, after solution and 
filtration of the silica, will be necessary. In this case the first 
and second filtrates are combined, nitric acid is added, and the 
solution is evaporated nearly to dryness. To the ore or nearly 
dry mass add 25 cc. of a solution of potassium chlorate in 
nitric acid, prepared by shaking an excess of the crystals with 
strong pure nitric acid in a flask. Add the solution gradually 
and do not cover at first, but warm gently until all violent 
action has stopped and greenish fumes cease coming off. Then 
cover with a watch-glass and boil on a hot iron plate to dryness, 
—overheating or baking should be avoided,—a drop of nitric 
acid adhering to the cover doing harm. Cool sufficiently and 
add 7 gms. of ammonium chloride, 15 cc. of strong ammonia- 
water, and 25 cc. of hot water, Keplace thevcover som sae 
casserole and boil for one minute, stirring with a rubber-tipped 
glass rod to break up all particles or clots of solid matter on 
the sides and bottom of the casserole and the cover. Filter 
into a flask of about 250 cc. capacity, and wash several times 
with a hot solution of ammonium chloride prepared as follows: 
Dissolve 10 gms. of ammonium chloride in 1000 cc. of water, 
and before using heat to boiling in a wash-bottle and render 
slightly alkaline with ammonia. Should a considerable pre- 
cipitate be produced it will carry down zinc hydrate with it. 
In the case of a small precipitate the amount of zinc which it 
retains may be disregarded. If a large precipitate forms it 
should be transferred from the filter to the original decom- 
posing vessel by means of a spatul, and wash-bottle, using as 
little water as possible. ‘The excess of water is evaporated off 
and the precipitate finally treated with the mixture of chlorate 
and nitric acid as before. The second precipitate is treated 
with ammonia, ammonium chloride, and water, filtered and 
washed as before, the second alkaline filtrate being combined 
with the first. A blue coloration in the filtrate indicates the 
presence of copper, which must be removed before proceed- 
ing with the titration. Add hydrochloric acid to neutralization 
(indicated by the gradual disappearance of the blue color), and 
then 10 cc. of hydrochloric acid in excess. If the solution is 


LINC. 209 


not sufficiently warm (about 70° C.) it should now be heated 
to that point. Now add from 20 to 4o gms. of test-lead and 
shake vigorously until all the copper is precipitated. The 
amount of test-lead and the amount of shaking necessary will 
of course depend upon the amount of copper present, which 
will be indicated by the depth of the blue color before neutral- 
ization. Aluminium-foil may be used for the precipitation of 
the copper in place of test-lead. In case aluminium is used it 
should be cut into strips of a convenient size, the strips being 
removed and washed after the copper is all precipitated. The 
copper can be removed from the foil when it is ready for use 
again, it being serviceable until it becomes too thin for further 
use. If test-lead is used it is best to use fresh lead for each 
determination. In case copper is absent the above treat- 
ment with test-lead or aluminium may be dispensed with. In 
this latter case it is best to add a piece of litmus-paper, two 
drops of methyl orange, or some suitable indicator to the 
alkaline solution, then hydrochloric acid until the solution is 
neutral, and finally an excess of 10 cc. of acid. The solution is 
now ready for the determination of the zinc with the standard 
solution of potassium ferrocyanide, as described above in 
standardization of the solution. A very good plan in titrating, 
when the per cent of zinc is not approximately known, is to 
pour off about half of the solution into a beaker and titrate 
roughly. This will give the approximate per cent of zinc, 
-when the balance of the fluid in the flask is added to the con- 
tents of the beaker and the titration proceeded with, a con- 
siderable, or such, quantity of the standard solution being 
added as the per cent of zinc, as approximately determined, 
will allow. ‘The flask is finally thoroughly rinsed out with 
water, the rinsings being added to the beaker, and the titration 
finished by adding a few drops of the standard solution at a 
time, testing a drop of the solution, after each addition, with the 
uranium-acetate solution. At the first indication of a brown 
color the addition of the ferrocyanide is stopped and the read- 
ing of the burette taken. If we have approximately the same 
bulk of solution and the same amount of free acid present in 


210 A MANUAL OF PRACTICAL ASSA VYING, 


the regular assay as we have in the standardization of the 
ferrocyanide solution, no allowance need be made for the 
quantity of excess of ferrocyanide (about two drops) necessary 
to color the indicator. 

Slags.—In the case of slags it is necessary to evaporate 
the solution of the slag (if the sample is obtained by sudden 
chilling, the acid solution; or, if fusion was necessary to decom. 
pose the slag, the solution of the fusion) to dryness, heat to 
dehydrate the silicic acid, and finally dissolve the dry mass in a 
little water and nitric acid. Now add the chlorate mixture 
and proceed as above. Unless this precaution be taken the 
results will invariably be low, probably owing to the gelatinous 
silica retaining a portion of the zinc solution. 

Ores containing Cadmium.—The acid solution, before 
adding test-lead or aluminium, is subjected to the passage of a 
rapid current of sulphuretted hydrogen. ‘This precipitates the 
cadmium as well as the copper. When the precipitation is 
complete the sulphide precipitate is filtered off and washed, 
when the filtrate is ready for titration as before, it being une 
necessary to expel the excess of sulphuretted hydrogen by 
boiling before proceeding with the titration. 

With many ores, especially the sulphide ores of the west, 
treatment with aqua regia is unnecessary in order to effect 
complete decomposition, simple treatment with the nitric-acid 
potassium-chlorate mixture being sufficient. 

A determination, except when a fusion is necessary to 
effect decomposition, or cadmium is present, may be made in 
30 minutes. | 

Manganiferous Ores.—Mr. G.C. Stone* proposes a modi- 
fication of the Von Schulz and Low method which presents 
some advantages, especially in the analysis of zinc-manganese 
ores, such as the New Jersey ores. 

The method is essentially as follows: 

Sulphide ores are best dissolved in hydrochloric acid and po- 
tassium chlorate, care being taken to have sufficient acid present 








* Journal Am. Chem. Society, Vol. XVII, page 473, June 1895. 


ZINC, 210a@ 


to insure keeping all the manganese in solution. Oxides, car- 
bonates, and silicates are dissolved in hydrochloric acid and 
oxidized by boiling with potassium chlorate. Ores containing 
franklinite or rhodonite must be first fused with sodium car- 
bonate and evaporated to dryness with hydrochloric acid to 
thoroughly decompose them; then taken up with hydrochloric 
acid in slight excess and boiled with potassium chlorate to in- 
sure oxidation of the iron. The iron and alumina are removed 
by precipitating with barium carbonate. The barium-carbonate 
solution is prepared by treating a pure salt, free from ammo- 
nium salts (as Merk’s), by suspending in water, warming for 
several hours with two or three per cent of its weight of 
barium chloride; this converts the alkaline carbonate present 
into chloride and the small excess of soluble barium salt present 
does not interfere. 

The thoroughly oxidized solution of the ore is washed into 
a 500-cc. flask, cooled, and barium carbonate, suspended in 
water, added until the precipitate curdles, an excess doing no 
harm. Fill to the 500-cc. mark, pour into a beaker, mix thor- 
oughly, allow to settle, decant the clear liquid through a dry 
filter, and take aliquot portions for titration. 

The solution should be filtered from the iron at once (to avoid 

precipitation of zinc) and should be titrated as soon as filtered. 
The titration for manganese is performed by standard potassium 
permanganate solution (see page 198), the result being the per- 
centage of manganese as calculated from the weight of ore 
taken. 

In a second portion, made slightly acid with hydrochloric 
acid, the zinc and manganese are titrated together by standard 
potassium-ferrocyanide solution. As manganese ferrocyanide 
is soluble in a large excess of hydrochloric acid, a considerable 
excess should be avoided. Five cc. added to 100 cc. of the 
solution does not cause any appreciable error; larger quantities 
are to be avoided. The titration is performed as described 
(page 209), except that a quite dilute solution of cobalt nitrate is 
used as an indicator in place of the uranium salt. A drop of the 
cobalt solution is placed on a white porcelain plate, and a drop 


2106 A MANUAL OF PRACTICAL ASSA YING. 


of the solution to be tested is added so that the drops touch, 
but do not mix; an immediately shown greenish line at the 
junction of the drops marks the end reaction. The solution 
should be cold—not warmer than the ordinary temperature of 
the laboratory. 

The manganese is precipitated as K,Mn,Fe,(CN),,; hence 
an amount of ferrocyanide that will precipitate four atoms of 
zinc will only precipitate three atoms of manganese. 

The calculation of results is best illustrated by an example: 
The strength of the ferrocyanide solution was I cc. = 0.00606 
gm. zinc. The strength of the permanganate solution was I cc. 
= 0.00I gm. manganese: 2.5 gms. of ore were dissolved and 
the solution was diluted to 500 cc.; 50 cc. of this solution was 
taken for the determination of manganese and 100 cc. for the 
determination of zinc. As 18.45 cc. (= 7.38 per cent Mn) was 
used in the first and 27.85 cc. was used in the second titration, 
it is necessary to deduct 9.61 cc. (for the 0.0369 gm. of Mn 
present in the 100 cc.) from 27.85 cc., leaving 18.24 cc. for the 
zinc, equal to 0.11053 gm., or 22.11 per cent zinc. 


CHAPTER XXII. 
NICKEL (Ni) AND COBALT (Co). 


NICKEL and cobalt are almost invariably associated with 
each other in ores and metallurgical products, and consequently 
a determination of either metal generally involves their separa- 
tion. A number of different methods for the separation and 
determination of nickel and cobalt have been proposed, but 
the writer believes the following to be as rapid and accurate as 
any: 

The material should first be examined for members of the 
sulphuretted-hydrogen group. If any members of this group 
are found to be present, it will be necessary to remove them 
before proceeding with the analysis. To remove the members 
of the sulphuretted-hydrogen group dilute the filtrate from 
the silica with water to about 60 cc., warm to about 70° C., and 
pass a rapid current of sulphuretted-hydrogen gas, allowing the 
solution to cool during the passage of the gas. Filter out the 
precipitated sulphides, wash thoroughly with dilute sulphur- 
etted-hydrogen water, and boil the filtrate, adding hydrochloric 
acid and chlorate of potash to oxidize the iron and sulphur. 
The solution is now ready to proceed with the analysis in the 
usual way. If no members of the sulphuretted-hydrogen group 
are present, this treatment is not necessary. 

Treat from I to 5 grammes of ore (according to the amount 
of Ni and Co which the ore contains) with pure concentrated 
sulphuric, nitric, and hydrochloric acids in a small flask similar 
to the flask used in the copper-assay. For I gramme of ore 


use about 5 cc. of sulphuric, 5 cc. of nitric, and 3 cc. of 
2II 


212 A MANUAL OF PRACTICAL ASSAYING. 


hydrochloric acid. Heat until copious fumes of sulphuric 
anhydride are given off, adding more sulphuric acid, if neces- 
sary, to avoid reducing the mass to dryness. Cool, dilute with 
cold water, filter, and wash thoroughly with hot water. 

Dilute the filtrate or the oxidized filtrate from the precipi- 
tated sulphides, if sulphuretted hydrogen was used, with water, 
and gradually add ammonia-water, with constant stirring, until 
the solution is decidedly alkaline. Filter out the precipitated 
ferric hydrate and wash slightly with hot water. Dissolve the 
precipitate with dilute hydrochloric acid, dilute with water, add 
pure sodium carbonate until a slight cloudiness is perceptible,and 
then add a drop of dilute hydrochloric acid to clear the solu- 
tion. Now add from 7 to 15 grammes of pure sodium acetate, 
and boil to precipitate basic acetates. Filter whilst hot, using 
the filter-pump if the precipitate is bulky. Wash with hot 
water, and dissolve the precipitate with dilute hydrochloric 
acid, and reprecipitate as basic acetates, as before. This second 
basic-acetate precipitation is unnecessary if the amount of 
iron and alumina is small; but if the first basic-acetate precipi- 
tate is large, it is necessary in order to insure all the nickel 
and cobalt passing into solution. Combine the three filtrates. 
and concentrate to 400 or 500 cc. by evaporation, acidify 
slightly with acetic acid, and boil. When boiling saturate the 
solution with sulphuretted hydrogen, continuing the boiling 
whilst passing the gas. Filter off and wash the precipitated 
sulphides of nickel and cobalt, and wash thoroughly with sul- 
phuretted-hydrogen water. To recover any possible traces of 
nickel or cobalt which may have escaped, acidify the filtrate 
with a little acetic acid and boil. Should any precipitate of 
sulphides be recovered by this treatment wash it and the main 
precipitate from the filter into a casserole, dry and burn the 
filters, add the ashes to the precipitates, and dissolve with 
nitrohydrochloric acid. Evaporate nearly to dryness to expel 
the excess of acid, dilute with water and add a solution of pure 
potassium hydrate, heat for some time, keeping the solution 
near the boiling-point, and then: filter and wash. Wash the 
precipitated oxides from the filter into a beaker, place the 


—_ = 


NICKEL AND COBALT, 213 


beaker under the funnel, and dissolve what remains on the 
filter with a saturated solution of pure potassium cyanide, 
allowing the solution to run through the filter into the beaker 
containing the oxides. Warm the beaker and its contents 
until the oxides are dissolved, and heat to boiling to expel the 
free hydrocyanic acid. Now add to the hot solution finely 
pulverized and elutriated red mercuric oxide, and boil. The 
whole of the nickel will be precipitated, partly as cyanide and 
partly as sesquioxide, the mercury combining with the free 
cyanogen. Filter off this precipitate, wash, dry, and ignite. 
The ignited precipitate is oxide of nickel (NiO). To obtain 
the weight of nickel, multiply the weight of this precipitate by 
0.78667. 

The filtrate from the precipitated nickel contains the cobalt 
in solution. Carefully neutralize it with nitric acid, so that the 
solution is not acid and not strongly alkaline. Now adda 
solution of mercurous nitrate as long as it produces a precipi- 
tate of mercury-cobaltocyanide. Filter, wash, and dry the 
precipitate, finally igniting in a strong current of hydrogen in 
a Rose crucible so as to reduce the precipitated cobalt to the 
metallic state. Weigh the metallic cobalt. 

Another good method is to concentrate the combined 
filtrates from the ammonia and basic-acetate precipitations to 
about 100 cc., render the solution decidedly alkaline by the 
addition of a little ammonia, transfer to a weighed platinum 
dish, and precipitate the nickel and cobalt together by passing 
a strong galvanic current, keeping the solution alkaline with 
ammonia. The battery used for the generation of the current 
is the same as that used in the precipitation of copper electro- 
lytically, two or three Bunsen cells making a very good battery. 

The nickel and cobalt are thrown down on the platinum in 
the form of a metallic coating. When they are completely 
precipitated remove the dish, wash it thoroughly with hot 
water, dry, and weigh it. The increase in weight of the dish 


_is the combined weights of the metallic nickel and cobalt. If 


it is necessary to determine them separately dissolve, the pre- 


214 A MANUAL OF PRACTICAL ASSA YING. 


cipitate in nitric acid and effect the separation and determina- 
tion as above. This is a very neat and accurate method. 

The ignited oxide of nickel is liable to contain impurities. 
To determine these, transfer the ignited oxide to a beaker, add 
water, and boil. Filter, and wash thoroughly with boiling 
water. Dry, and ignite the oxide of nickel again. The loss in 
weight is probably due to some adhering alkali. Now dissolve 
the oxide of nickel in nitrohydrochloric acid, boil, dilute, filter, 
wash, dry, ignite, and weigh any undissolved silica. Deduct 
this weight from the weight of the oxide of nickel. Dilute 
the filtrate and add a large excess of ammonia, and filter out 
any precipitate of alumina or ferric hydrate which may form. 
Wash, dry, and ignite this precipitate and deduct its weight 
from the weight of the nickel oxide. From the true weight of 
the nickel oxide, as thus determined, calculate the weight of 
the metallic nickel. 


CHAPTER XXIII. 


CALCIUM (Ca). 


LIME (CaO) is usually determined gravimetrically by pre.- 
cipitating it as calcium oxalate, converting the precipitate 
into a sulphate, and weighing as calcium sulphate; or volu- 
metrically by precipitating it as calcium oxalate, and deter- 
mining, after filtering and washing, the oxalic acid combined 
with the calcium by means of a standard solution of potassium 
permanganate. The second method is much more rapid than 
the first, and is fully as accurate, if proper care be observed. 
(See Fresenius, Wiley & Sons’ edition of 1881, page 828.) 

The solution of permanganate used may be the same as is 
used for the determination of iron, and may be standardized 
in the same manner. A comparison of the following equation 
with the one for the oxidation of ferrous iron to ferric iron 
by permanganate of potassium (see Part II, Chapter XVI) 
will show that one cc. of the permanganate solution is equal 
to exactly half as much lime (CaQ) as iron, the molecular 
weight of lime and the atomic weight of iron being the same: 


6CaC,O, + 8H,SO, -+- K,Mn,0, = 
5CaSO, + 2MnSO, + K,SO, + 2CO, + 8H,O. 


Consequently, if 1 cubic centimetre of permanganate solution 
equals 0.010 gramme of iron it will equal 0.005 sramme of 
lime. 

Limestones.—One gramme of the limestones is treated as 
described in Chapter I, on Silica. The iron and alumina are 
precipitated out of the filtrate from the silica, as described 

; 215 


216 ‘ A MANUAL OF PRACTICAL ASSAYING, 


in Chapter XVII, on Alumina. The filtrate from the precipi- 
tated hydrates of iron and aluminium is then ready for the 
precipitation of the calcium, provided its bulk is not much 
over 100 cc. If much iron or alumina is present it is safer to 
dissolve the precipitated hydroxides in a few cc. of hydrochloric 
acid, and reprecipitate with ammonia, combining the filtrate 
from this precipitate with the first filtrate for the determination 
of the lime. A cubic centimetre of ammonia should be added, 
and the solution brought toa boil. Ifa precipitate other than 
aluminium or ferric hydrate forms (such a precipitate should be 
filtered out, and added to the previous precipitate of hydrates), 
acidify slightly with hydrochloric acid, and make alkaline with 
ammonia. This is done to introduce sufficient ammonium 
chloride to prevent the precipitation of magnesium hydrate. 
The lime is then precipitated as an oxalate by the addition of 
ammonium oxalate or oxalic acid. If oxalic acid is used there 
should be a considerable excess of ammonia present in order 
that the solution may be alkaline after the addition of the 
oxalic acid. If magnesia is present the ammonium oxalate 
should be in considerable excess. [According to Cairns, 40 cc. 
of a solution of ammonium oxalate prepared by dissolving one 
part of oxalate in twenty-four of water.] This is not only to 
precipitate all of the lime as oxalate, but to convert all of 
the magnesia into oxalate, which is soluble. Heat nearly to 
boiling for a few minutes, and then filter. If the solution was 
brought to a boil before precipitation, and a good filter-paper 
is used, there will be no danger of the calcium oxalate running 
through the filter-paper. Provided magnesia is not present, 
less ammonium oxalate should be used, and the filtration may 
be proceeded with as follows: filter, and wash the precipitate 
out of the beaker on to the filter-paper with boiling water, then 
wash the precipitate on the filter-paper with boiling water until 
the washings no longer give a reaction for oxalic acid. Remove 
the filter and contents from the funnel, and spread out on 
-a watch-glass somewhat larger than the paper. Wash into a 
beaker with hot water from a wash-bottle with a fine jet, and 
after all the precipitate is removed from the paper, or all that 


CALCIUM. 217 


can be in this way, wash the paper with some dilute sulphuric 
acid, transferring the washings to the beaker. Sometimes it is 
difficult to remove the last traces of calcium oxaiate from the 
paper with sulphuric acid. In such acase a few drops of dilute 
hydrochloric acid may be added to the paper. The contents 
of the beaker are now diluted with warm water to about 100 
cc., 15 cc. sulphuric acid added, and the solution heated to 
about 70° C. The solution is now ready for titration with a 
standard solution of potassium permanganate. This titration 
is performed in the same manner as described for the determi- 
nation of the standard of the permanganate solution by means 
of oxalic acid (see Chapter XVI). If magnesia is present it is 
always safest, and is in fact absolutely necessary where an 
accurate determination is to be made, to dissolve the first 
precipitate of calcium oxalate in hydrochloric acid, and repre- 
cipitate, on account of the magnesia which has been carried 
down with the first precipitate. To do this wash the precipitate 
inte a beaker as before (such care in washing the precipitate as 
before is not necessary; in fact, it need only be filtered), and 
dissolve in as little hot dilute hydrochloric acid as possible. 
Dilute to about 50 cc. with boiling water, make alkaline with 
ammonia, add 20 cc. of ammonium-oxalate solution, and heat 
nearly to boiling. Then filter, wash, and determine the lime 
as above. 

The second filtrate is to be combined with the first for the 
determination of magnesia. (See Chapter XXIV.) 

If desirable the lime can be determined gravimetrically, as 
described below, although the experience of the writer is that 
the volumetric determination gives fully as accurate results, and 
is more rapid. 

Clays, Cements, Feldspar, etc.—Treat the substance as 
described in Chapter I, and, after combining the filtrate from 
the insoluble, and the silica by fusion, proceed as above. 

Ores.—For the determination of lime in ores the method 
as given for limestone may be used. In the cases of lead ores 
it is necessary to first remove the lead. 


218 A MANUAL OF PRACTICAL ASSA YING. 


Slag.—For the determination of the lime in a slag the fob 
lowing method is generally used, and answers all chau 
for technical purposes: 

The filtrate from the silica (see Chapter I) is heated to boil- 
ing, made alkaline with a slight excess of ammonia, and acidi- 
fied with a slight excess of a saturated solution of oxalic acid. 
Ammonia is then added until the solution is slightly alkaline, 
and then a solution of oxalic acid until the iron precipitate is 
dissolved. The solution is then heated to boiling, filtered and 
washed, the lime being determined.volumetrically as above. 
The precipitated calcium oxalate should be white, otherwise 
iron, manganese, etc., have not been dissolved, showing an in- 
sufficiency of oxalic acid. Whilst this latter method is not 
absolutely accurate, it is generally sufficiently accurate for 
technical purposes, and is extremely rapid; a determination of 
silica and lime ina slag having frequently been made by the 
writer in from an hour and fifteen minutes to an hour and a 
half whilst doing other work. 

For the determination of the lime gravimetrically, obtain 
the precipitate of calcium oxalate as described above. It is 
necessary to wash all of the precipitate out of the beaker and on 
to the filter. Some of the precipitate will usually adhere to the - 
sides of the beaker, and can generally be removed by rubbing 
with a glass rod provided with a rubber on the end. When this 
treatment fails to remove all of the precipitate from the sides 
of the beaker, dissolve it in a few drops of hydrochloric acid, 
add a few cc. of boiling water, making alkaline with ammonia, — 
and precipitate with ammonium oxalate. When all of the pre- 
cipitate is transferred to the filter, wash until the washings no 
longer give a reaction for oxalic acid, and finally wash the pre- 
cipitate down into the point of the filter. Dry the filter-paper 
and its contents in a hot-air bath, and when thoroughly dry 
remove from the funnel. Transfer the precipitate to a weighed 
platinum crucible by inverting the filter-paper over the crucible 
and gently rolling between the-fingers. Roll the filter-paper 
and the small amount of precipitate adhering to it into a ball, 
and ignite on the lid of the crucible over the flame of a burner 


CALCIUM, 219 


until white. Add the filter-ash to the precipitate in the cruci- 
ble, and thoroughly moisten the precipitate with strong c. p. 
sulphuric acid, place the lid on the crucible, and expel the 
excess of acid by heating over a burner, allowing the flame to 
touch only the edge of the crucible cover. After expelling all 
free sulphuric acid, ignite strongly over a blast-lamp or in the 
muffle, cool, and weigh. 

This weight, after deducting the known weights of the cruci- 
ble and filter-ash, will be the weight of the calcium sulphate. 
Multiply this weight by 0.41176, and the result will be the 
weight of the lime. 


“~*~ 


CHAPTER XXIV. 


MAGNESIUM (Mg). 


MAGNESIA (MgO) is universally determined by precipitating 
it as ammonium-magnesium phosphate, converting it into mag- 
nesium pyrophosphate (Mg,P,O,) by ignition, and weighing as 
such. The preparation of the solution for the precipitation of 
the magnesia will depend upon what metals are present. The 
metals of the sulphuretted-hydrogen group, the ammonium- 
sulphide group, and barium, strontium, and calcium, should be 
removed before the precipitation of the magnesia. 

The solution should contain ammonium chloride and an 
excess of free ammonia, and should be cold before adding the 
hydrodisodium-phosphate solution, which may be prepared by 
dissolving one part by weight of the salt in ten parts of water. 
After adding the phosphate solution, agitate by stirring with a 
glass rod, care being exercised not to touch the sides of the 
beaker with the rod, as that will cause crystals of ammonium- 
magnesium phosphate to adhere to the sides of the beaker, and 
they will be difficult to remove. Cold, and frequent agitation 
of the solution, facilitate the precipitation, and it isa good plan 
to set the beaker in a dish containing ice-water or a freezing 
mixture and stir from time to time. Several hours’ (from 2 to 
12) standing in the cold are necessary to complete the precipi- 
tation, the time depending to a great extent on the amount of 
magnesia present. After allowing to stand a sufficient length 
of time, remove a few drops of the clear liquid with a piece of 
glass tubing, transfer to a test-tube, and add two or three drops 
of magnesia mixture. This is prepared by dissolving one 
eramme of magnesium sulphate and one gramme of ammonium 


chloride in 8 cc. of water and adding 3 cc. of ammonia. If a 
220 


MAGNESIUM. 221 


precipitate forms it shows that sufficient phosphate solution 
was added. Should no precipitate form add 5 cc. of the phos- 
phate solution, stir, and proceed as before. Provided one 
gramme of substance was taken, and the magnesia is not over 
30 per cent, 30 cc. of the phosphate solution (prepared as above) 
and added at first will serve to precipitate all of the magnesia. 
Filter on a small filter and wash with dilute ammonia, prepared 
by adding two parts of water to one part of ammonia, until the 
washings no longer show a precipitate upon the addition of a 
few drops of silver-nitrate solution, after having previously 
acidified them with c. p. nitric acid. Dry the filter and precipi- 
tate as in the case of calcium oxalate (see Chapter X XIII), and 
when dry transfer the precipitate to a weighed crucible, and 
ignite the filter on the lid of the crucible until white. Add the 
filter-ash to the contents of the crucible, and ignite strongly 
until the contents of the crucible are white or nearly so. 
Should the precipitate be of a dark color, moisten with a few 
drops of nitric acid, and, after having carefully evaporated off 
the excess of acid, ignite again strongly until the precipitate 
assumes a light-gray color. Now cool and weigh the crucible 
and its contents. After deducting the known weight of the 
crucible and filter-ash, the remainder will be the weight of the 
magnesium pyrophosphate. Multiply this weight by 0.36036, 
and the result will be the weight of the magnesia (MgO). From 
this calculate the percentage. 

Slags.—As these contain all the impurities of the ores and 
fluxes from which they were produced, to a more or less large 
extent, a separation of the metals of the different groups will 
be necessary before precipitating the magnesia. Dilute the 
filtrate from the silica obtained as described in Chapter I, with 
distilled water, to about 200 cc., and pass a rapid current of 
sulphuretted-hydrogen gas through the solution, filter off the 
precipitated sulphides, and oxidize the filtrate as described in 
Chapter XVII. Transfer the solution to a flask of not less 
than 500 cc. capacity, and add a saturated solution of sodium 
carbonate until a slight permanent precipitate forms. Dissolve 
this precipitate in a slight excess of acetic acid, add about Io 


222 A MANUAL OF PRACTICAL ASSAYING. 


srammes of sodium acetate, dilute to about 300 cc., and heat to 
boiling. Continue to boil for a few minutes, and filter whilst 
hot, washing thoroughly with hot water.* Boil the filtrate 
from the precipitated basic acetates, add a few grammes of 
sodium acetate, and add bromine-water until the solution has 
a decided yellow color. Continue to boil and add bromine- 
water for some time, until the bromine no longer produces a 
precipitate of manganese oxide. Filter out the precipitate of . 
manganese oxide, and, to be sure that the filtrate contains no 
manganese, neutralize it with sodium carbonate, acidify with 
acetic acid, boil, and add bromine. Ifa precipitate forms, pro- 
ceed as before. When the solution is free from manganese 
acidify it thoroughly with acetic acid, boil, and while boiling 
pass a rapid current of sulphuretted-hydrogen gas. The gas 
should be passed for from 10 to 30 minutes, depending upon 
the amount of zinc present. By this means the zinc is pre- 
cipitated as a sulphide, and can be filtered out. Wash with 
hot water by decantation once or twice, and then wash 
thoroughly with sulphuretted-hydrogen water. It is best to 
remove the beaker containing the bulk of the solution from 
beneath the funnel, and filter into a small beaker, changing the 
beaker frequently on account of the liability of the zinc sulphide 
to run through the filter. To the filtrate from the zinc sulphide 
add 1 cc. of hydrochloric acid, boil, and add bromine-water to 
oxidize the sulphur. Ifa precipitate of sulphur forms, filter it 
out. The solutions now contains lime and magnesia. The 
lime is precipitated as calcium oxalate in the manner described 
in Chapter XXIII, the precaution being observed to dissolve 
the precipitate of calcium oxalate in a little hydrochloric acid 
and reprecipitate, on account of the magnesia which may be 
precipitated together with the lime. The filtrate from the 
calcium oxalate is now ready for the precipitation of the mag- 
nesia in the manner described above. 





* When considerable quantities of iron, alumina, and magnesia are present, 
it is best to dissolve the precipitate in a little hot dilute hydrochloric acid, and 
reprecipitate as basic acetates in the manner described, adding the second fil- 
trate to the first. 


MAGNESIUM. 223 


Silver, Copper, and Lead Ores.—Proceed as above, except 
that when manganese and zinc are not present the lime can be 
precipitated in the filtrate from the precipitate of the basic 
acetates of iron and.alumina, the treatment with bromine, and 
subsequently with sulphuretted hydrogen, being omitted. 

Limestones, Clays, Cements, etc.—As these substances 
seldom contain any of the metals of the sulphuretted-hydrogen 
group, proceed as in the determination of lime in limestones 
(see Chapter XXIII), and precipitate the magnesia in the 
filtrate from the calcium oxalate as above. 

The above examples will serve for nearly every case likely 
to arise. 


CHAPTER XXV. 


BARIUM (Ba). 


BARIUM is universally precipitated as a sulphate and 
weighed as such (BaSQ,). 

The following method will serve for all ores and furnace. 
products: 

Dissolve as described in Chapter I, taking the precaution 
to add a few drops of sulphuric acid in addition to the hydro- 
chloric and nitric acids, to precipitate the barium as sulphate 
with the silica. Evaporate to dryness, dissolve in hydrochloric 
acid, boil, add water, filter and wash thoroughly, and ignite. If 
the silica is to be determined, weigh the insoluble residue and 
determine the barium as follows: Fuse the insoluble residue 
with from one to five grammes (depending on its amount) of 
carbonate of soda (see Chapter I). Dissolve.the fusion in hot 
water and boil. Filter through a small filter, and wash until 
the washings no longer show a reaction for sulphuric acid, which 
can be determined by acidifying some of the washings in a test- 
tube with hydrochloric acid and adding a few drops of barium- 
chloride solution. Should no precipitate form, the barium car- 
bonate remaining behind on the filter is washed sufficiently. 
Dissolve the precipitate on the filter in dilute hydrochloric 
acid, allowing the solution to run into a small beaker. The 
funnel should be covered with a watch-glass to prevent loss by 
effervescence when the acid is added. Wash off the watch-glass 
and sides of the funnel with hot water, and finally drop a few 
drops of hydrochloric acid around the edges of the filter-paper 


224 


BARIUM. 2215 


and wash thoroughly with hot water. The filtrate should be 
perfectly clear, and should be brought to a boil when it is ready 
for the precipitation of the barium, which can be accomplished 
by adding sulphuric acid to the solution. From a few drops 
to two cc. of dilute sulphuric acid should be added, depending 
on the amount of barium present. The solution should be 
allowed to stand for some time until the precipitate partially 
settles before filtering. If a good filter-paper, such as Schlei- 
cher & Schuell’s, is used, it is not necessary to allow the solu- 
tion to stand until the precipitate settles absolutely, as with 
such a filter it will seldom run through. A good plan is to 
filter off into a small beaker, changing the beaker frequently, so 
if any of the precipitate should run through the filter it will 
not be necessary to refilter such a large amount of solution. 
The first filtrate should be tested with a few drops of sulphuric 
acid to determine whether all of the barium has been precipi- 
tated. After the solution is all filtered wash what remains in 
the beaker on to the filter with hot water, and wash the pre- 
cipitate on the filter once or twice with hot water, finally wash- 
ing the precipitate down into the point of the filter. Dry, and 
ignite in the manner described for the precipitate of magnesia 
pyrophosphate (Chapter XXIV). A small filter-paper should 
be used, as the carbon of the filter-paper is liable to reduce 
barium sulphate to a sulphide. When much of the precipitate 
adheres to the filter-paper moisten its ash, after ignition, with 
a few drops of nitric acid, and ignite again. ‘The precipitate 
should be perfectly white, and can be transferred from the 
crucible to the watch-glass of the balance and weighed directly. 
This weight, less the known weight of the filter-ash, will be the 
weight of the barium sulphate. To obtain the weight of the 
baryta (BaO) multiply this weight by 0.65636. 

For the rapid determination of baryta and silica in lead 
slags the following method answers for technical purposes: 
Treat 0.5 gm. with water and hydrochloric acid in a casserole, 
heat, add water, filter, and determine the silica as usual. This 
insoluble residue may be considered as silica. Treat another 


220 A MANUAL OF PRACTICAL ASSA YING. 


portion (0.5 gm.) with water, hydrochloric acid, and a few 
drops of sulphuric acid. Evaporate to dryness, heat, dissolve 
in water and hydrochloric acid, and determine the insoluble 
residue as usual. This insoluble residue may be considered as 
consisting of silica and barium sulphate. 


Cha RPE ROX XVI. 


POTASSIUM (K) AND SODIUM (Na). 


ONE of the two following methods will be used, according to 
whether the substance is decomposed by acids or not: 

First Method.—7ze Substance is decomposed by Acids.— 
Dissolve from 0.5 to 5.0 grammes in hydrochloric acid, add 
bromine or chlorine water, and heat to boiling. Evaporate to 
dryness if necessary, and proceed asin the determination of 
silica (Chapter I). To the filtrate from the silicaadd ammonia in 
slight excess (if any members of the sulphuretted-hydrogen 
group are present they must be removed, as in the case of de- 
termination of alumina, Chap. X VII), and anmonium carbonate, 
and allow to stand for a few hours. Filter, wash, evaporate 
the filtrate and washings to dryness in a platinum dish, and ex- 
pel the ammonia salts by igniting to a point just below redness. 
Dissolve in water, add solution of barium hydrate until the 
fluid is decidedly alkaline, filter and wash well, and add to the 
filtrate solution of ammonium carbonate as long as it produces 
a precipitate ; allow the solution to stand for a short time, filter 
out the barium carbonate, and wash it until the washings do 
not render silver nitrate turbid. Now add a few drops of 
hydrochloric acid to the filtrate,and evaporate it to dryness 
in a weighed platinum dish, ignite to a slight-red heat, cool 
and weigh the mixed chlorides of sodium and potassium. 
Where an accurate determination is required, it is best to dis- 
solve the mixed chlorides in water and repeat the treatment 
with barium hydrate and ammonium carbonate, and again evap- 
orate and weigh. | 


The weight of sodium and potassium present may now be 
227 


228 A MANUAL OF PRACTICAL ASSAYING. 


determined indirectly as follows: Dissolve the combined chlo- 
rides in warm water, add a few drops of a saturated solution of 
potassium chromate, and add from a burette a standardized 
solution of silver nitrate until the red color of silver chromate 
appears. From the number of cc. of standard silver nitrate-solu- 
tion used calculate the weight of chlorine present, as described 
below. The weight of chlorine present having been thus de- 
termined, the weights of the sodium and potassium present may 
be calculated as follows: Suppose we have found I.0 gramme 
of sodium and potassium chlorides and 0.563 gramme of chlo- 
rine present in the combined chlorides. 


35.4 (at. wt. Cl): 74.4 (mol. wt. KCl): : 0.563 (Cl found): #. 
ize ge 20. 


If all of the Cl present were combined with K, the weight 
of the chloride would amount to 1.18326. As the combined 
chlorides weigh less, NaCl is present, and in a quantity pro- 
portional to the difference (dif. = 1.18326 — I.0 = 0.18326). 
The difference between the molecular weight of KCl and that 
of NaCl (16.0) is to the molecular weight of NaCl (58.4) as the 
difference found is to the NaCl present; or, 


16 : 5.84 :: 0.18326: x (NaCl present). 
« (NaCl present) = 0.67015 gms. 
KCl present = 1.0 — 0.67015 = 0.32985. 


The above illustrates the method of calculating results. 

To prepare the standard silver-nitrate solution, dissolve from 
17 to 18 grammes of pure nitrate of silver in one litre of dis- 
tilled water. To standardize the solution, dissolve I gramme 
of pure fused sodium chloride in one litre of water, pour exact- 
ly 100 cc. of the solution into a beaker, add three drops of a 
saturate solution of potassium chromate, and dropin from the — 
burette the silver solution until the red color of silver chromate 
appears. The known quantity of chlorine, in the 100 cc. of salt 
solution, divided by the number of cc. of silver solution used, 
will give the value of 1 cc. of the latter. 


—S =< -- —- — 


POTASSIUM AND SODIUM. 229 


In the case of analyses where extreme accuracy is required 
the potassium may be determined directly as follows, and the 
sodium by difference: Dissolve the combined chlorides (after 
having weighed them) in warm water, and if the solution is com- 
plete, transfer it to a small casserole, add 3 to 4 drops of hydro- 
chloric acid and a solution of potassium tetrachloride (as much 
as contains an amount of the salt equal to about four times the 
weight of the combined chlorides) and evaporate on the water- 
bath until the mass is pasty. Now add to the casserole about 
50 cc. of 85 per cent alcohol, and heat for a few minutes on the 
water-bath. Then wash into a small flask (which we will desig- 
nate as A) the contents of the casserole with alcohol (85 per 
cent), and cork the flask immediately. After the precipitate of 
potassium platinochloride has entirely settled, and the fluid 
shows by its yellow color that sufficient platinum tetrachloride 
has been added, pour off the clear fluid into a small flask 
marked B, as completely as possible without transferring any 
of the precipitate, cork it, and allow it to stand long enough for 
any particles of potassium platinochloride, which may have 
passed over with the fluid from flask A, to subside. Then pour 
ifemiaskesie20 Or 30\cc. of 85 per cent alcohol, cork it, and 
after agitating it gently set it aside until the contents of flask 
B are disposed of. Pour the contents of B into a dish, add 
about Io cc. of water, and proceed to evaporate off the alcohol 
on a water-bath. Should there be any particles of the precipi- 
tate in the fluid, first pour off as muchas possible into the dish, 
without disturbing the precipitate and evaporate it as above, and 
pour the rest, with the precipitate, on a filter. Add this fil- 
trate to the fluid already evaporating. Keep the funnel covered 
with a glass while filtering. After all the fluid has thus been 
transferred to the dish for evaporation, pour upon the same 
filter the contents of flask A, washing the precipitate onto the 
filter with 85 per cent alcohol. Dry the filter and contents in 
an air-bath at 100° C. Ignite the dry precipitate, rolled up in 
the filter, in a weighed crucible, applying the heat very gently 
at first, and keeping the crucible covered until the filter-paper 
is charred. Then remove the cover and ignite at a higher heat 


230 A MANUAL OF PRACTICAL ASSAYING. 


until the filteris entirely consumed. Allow the crucible to cool, 
add a little oxalic acid, heat gently at first, until the water of 
crystallization of the oxalic acid is expelled, and then more 
intensely until the acid is decomposed and all the carbon con- 
sumed. Cool the crucible, and wash by decantation with hot 
water as long as the wash-water becomes turbid from the forma- 
tion of silver chloride when treated with silver nitrate. By. this 
means the double chloride is decomposed, and all the potas- 
sium and chlorine washed out, leaving only spongy platinum. 
Heat alone fails to decompose the compound completely. 
After the platinum is sufficiently washed, dry the crucible and 
contents, and ignite until everything is consumed but spongy 
platinum. Cool and weigh. This weight, less the known 
weight of the crucible and filter-ash, will be the weight of the 
platinum combined with the potassium as potassium-platinic 
chloride (PtCl,,2KCl). To obtain the weight of the potas- 
sium multiply the weight of the platinum found by 0.39594. 

After all the alcohol has been expelled from the original 
filtrate by evaporation, as directed above, add 1 cc. of platinum- 
tetrachloride solution and a small quantity of pure sodium 
chloride; continue the evaporation to pasty consistency, treat 
with alcohol, and proceed as directed for the treatment of the 
main precipitate. The sodium chloride has a tendency to 
prevent the decomposition of the platinum chloride while 
evaporating. 

Should the. solution of the combined chlorides be incom- 
plete, filter, and evaporate the filtrate to dryness, as directed; 
weigh, and dissolve in warm water. Now determine the potas- 
sium, as directed above. 

Second Method.—7vze Substance ts not entirely decal 
by Acitds—The substance can be fused with sodium carbonate 
and the silica separated as usual (Chap. I), and the determina- 
tion proceeded with as above; or the method of Prof. J. L. 
Smith* can be adopted. This method is as follows: Treat 


* Am. Jour. Sci. and Arts, Vol. I, p. 269 (1871); Crooks, Select Methods, 
D. 409. 


POTASSIUM AND SODIUM. 231 


0.5 to 1.0 gm. of finely pulverized silicate in an agate or 
glazed porcelain mortar with an equal amount of granular 
ammonium chloride, rubbing the two together intimately. 
Add eight parts of pure calcium carbonate in three or four 
portions, mixing thoroughly after each addition. Transfer 
the contents of the mortar completely to the crucible, and tap 
gently until its contents are settled. It is then clasped bya 
metallic clamp in an inclined position, and the heat of a small 
Bunsen burner is now brought to bear upon the crucible just 
above the top of the mixture, and gradually carried toward the 
lower part, until the ammonium chloride is completely decom- 
posed, which takes about five minutes. The heat is now raised 
gradually to a bright red, and kept there for about forty min- 
utes. It is best not to have too intense a heat, as that would 
vitrify the mass too much. ‘The crucible is now cooled, and 
when cool its contents will be found to be more or less 
agglomerated, in the form of a semi-fused mass. The mass is 
now transferred to a small casserole, and what adheres to the 
crucible is removed with warm distilled water, and sufficient 
water added to bring the bulk of the solution up to about 
75 cc. The contents of the casserole are now brought to the 
boiling-point, when the mass will begin to slack. After the 
mass is completely slacked and disintegrated, the analysis is 
proceeded with as follows: Filter off the contents of the casse- 
role on a good-sized filter, and‘ wash well with distilled water. 
The filtrate will contain in solution all the alkalies, with some 
chloride and hydrate of lime. Proceed to determine the 
potassium and sodium in this filtrate in the manner described 
in the First Method, by the addition of ammonium carbonate, 
etc. 


PAT Cait 


CHAPTER I. 


ASSAY OF BASE BULLION. 


FOUR samples (see Fig. 7) are cut from the small sample 
bar with a cold-chisel. From each of these samples 4 assay- 
ton is accurately weighed out for cupellation, it being a good 
plan to pound each sample into a cube before finishing the 
weighing. 

Cupellation.—Each 4 A. T. sample is now cupelled sepa- 
rately. In the case of impure bullion each sample should be 
scorified with a little borax before cupellation. In case the 
lead is very impure and contains a good deal of copper, a little 
test-lead will help the scorification. Some assayers prefer to 
scorify all samples before cupellation, contending that the loss 
of silver in scorification is less than the loss in cupellation. 

The cupels should weigh about 20 gms. each, and should 
be heated in the muffle before introducing the sample for 
cupellation. After dropping the samples into the cupel the 
door of the muffle should be closed until the samples are 
melted and cupellation begins. As soon as the samples begin 
to cupel the door is opened, and the cupellation is contin- 
ued at the proper temperature until the buttons “brighten.” 
The temperature of cupellation should be properly regulated. 
The cupels should always show “ feather litharge” around the 
edges, which they will not do if the temperature is too high. 
On the other hand, the temperature should not be too low, as 

232 


ASSAY OF BASE BULLION. 233 


in this case the loss of silver will be high, and the buttons are 
apt to “freeze” and ruin the assay. The proper temperature 
is something which can only be learned by experience. When 
the bullion is rich and the buttons, consequently, large, it is 
a good plan to have some cupels in the rear of the muffle, 
to cover the cupels containing the buttons just after they 
“brighten.” The cupels should be placed in a hot part of the 
muffle just before “ brightening,’ and should be gradually 
removed after “brightening,” in order to prevent “spitting.” 
A button which has “spit” or “sprouted” should always be 
rejected. When the cupels are cool the buttons are ready for 
weighing. 

Weighing.—The buttons are best removed from the cupel 
by means of a pair of pliers, and should be brushed off witha 
wire-brush to remove any particles of litharge or bone-ash 
which may adhere to the bottom. The buttons are now ready 
for weighing on the button-balance, and should agree together 
closely. The agreement should be within about 0.5 ounces on 
a bullion of from 200 to 400 ounces. After weighing, the but- 
tons should be flattened out with a few light blows, when they 
are ready for parting. 

Parting.—The parting can be performed in a small porce- 
lain crucible or, preferably, a glass matrass or test-tube. Two 
of the flattened buttons are introduced into each matrass, and 
c. p. nitric acid of 20° Baumé added. The matrass is now grad- 
ually warmed on an iron plate or sand-bath until the silver is 
all dissolved. The contents of the matrass are now boiled fora 
few minutes and then removed from the heat. After shaking 
gently to bring all the fine particles of gold into one mass, 
the solution is poured off. Fresh acid of 32° Baumé is now 
added, and the gold boiled for three minutes. It is again 
brought into one mass, if necessary, and the acid decanted off. 
The gold is now washed three times by decantation with dis- 
tilled water (free from chlorides), the matrass filled with dis- 
tilled water and inverted in a small porcelain crucible. After 
the gold hassettled to the bottom the matrass is removed and 
the water poured off, the last drops of water being readily re- 


234 A MANUAL OF PRACTICAL ASSA YING. 


moved by suction, through asmall piece of glass tubing drawn 
to a point at the end. The crucible is dried, and finally ignited 
at a red heat, when the gold is ready for weighing on the gold 
balance. The duplicates should agree almost exactly. 

Special Method.—In the case of extremely impure bullion, 
this method may have tobe adopted. Prepare the sample as 
described in Part I, Chapter II, weighing the dross and the bar 
separately. Weigh out four samples, of 4 A. T. each, of the 
dross, scorify, cupel, and part, as described above. Determine 
the gold and silver in the bar as described above. 

The manner of calculating the results is best illustrated by 
an example : 


Bariweighs ..iccuseu eect ae ee 4.25 Ibs. 
Dross:weighss @. sank siete eee 1.50% 





Total weight of sample (after melting). 5.75 lbs 


Bar-assays: 


J.C de RES AEAN Co5 oy patient A 8 806.00 0Z, 
AU era ohare alain Wants ee ete re citi reer SSO ie 
re = 0.8606 
Then aa X 405 = 0.800625, / 
Sh X 806 = 0.6045, 


2000 


the total ounces of silver in the bar and dross. 
Hence the total ounces of silver in the sample 


= 0.86025 + 0.6045 = 1.465125. 
2000 
Now T.AO5125 Xie eS OOlOrs 
405125 5.78 509 


the ounces of silver, per ton of 2000 pounds, in the sample. 


ASSAY OF BASE BULLION. 235 


In the same manner we have for the gold 


‘ 





eT 5 == Ra id 
yea hOi==,0.002125, and ae Mass5 = 0.002025. 
Hence 
2000 
0.002125 + 0.002625 =0.00475, and 0.00475 x are = ey 


the assay-value of the sample in ounces gold per ton. 
Hence the assay-value of the bullion is: 


The results may also be calculated according to the formule 
given in Part III, Chapter VIII, in which case the bullion and 
dross are weighed in grammes. 


CHAPTER II. 


ASSAY OF SILVER BULLION, 


For the determination of silver in silver bullion any of the 
following methods are applicable, but the first two are the 
only ones generally used in the United States. 

The first method is universal in its application, and is the 
method generally adopted by our Western metallurgical estab- 
lishments, although some refiners use the second method, whilst 
some works use both the first and second methods, using one 
as a check on the other. 

The first method is preferable when the bullion contains 
mercury, as in the case of retorted bullion from a pan-amalga- 
mation mill. 

The second method is the one which has been adopted by 
the U. S. Government for the determination of the fineness of 
silver bullion in the U. S. mints and assay-offices. 

The fineness or silver and gold contents of the bullion is 
always reported in thousandths ; i.e., so many degrees or parts 
of silver or gold in one thousand parts of bullion. For example, 
we say a bullion is g9go silver and 5 gold fine; that is, it con- 
tains 99 per cent of silver and 0.5 per cent of gold. 

The sample of bullion should always be annealed, and ham- 
mered or rolled out thin so that it can be cut readily with a 
pair of scissors. A small set of rolls, to be kept only for this 
purpose, will be found very convenient when many assays are 
to be made. 

First Method: By cupellation with pure lead. Fire-assay. 

236 


SO) iad 


ASSAY OF SILVER BULLION. 237 


Second Method: Volumetrically by means of a standard 
solution of sodium chloride. Gay-Lussac’s method. 

Third Method: Volumetrically by means of a standard so- 
lution of potassium sulphocyanide. Volhard’s method. 

The first and second methods require a preliminary assay 
to determine the approximate fineness of the bullion, unless 
this is known. The third method requires no preliminary 
assay. 

Preliminary Assay.—To determine the approximate fine- 
ness of the bullion weigh out 0.500 gramme of bullion (the 
bullion and buttons should be weighed on the button-balance), 
wrap in from 5.0 to 10.0 grammes of pure lead-foil, and cupel 
in the muffle-furnace, using a small cupel weighing about 10 to 
12 grammes.’ The cupel should be hot before placing the 
button in it, and the door of the muffle should be closed until 
cupellation commences. As soon as cupellation begins the 
door is opened and the cupel moved to the front of the muffle. 
The temperature is the most important point in this operation. 
‘The assay should run sufficiently cold to allow feather litharge 
to form on the cupel, but not so cold that there will be danger 
of the button freezing. The proper temperature is something 
which can only be gauged by experience; after considerable 
practice with this method the assayer will be able to control the 
temperature within comparatively narrow limits. Toward the 
latter part of the cupellation and just before the button 
brightens the cupel should be moved backinthe muffle. After 
the play of colors on the button has ceased, the button should 
be covered with a hot cupel; but before covering, it should be 


allowed to remain for about a minute to remove the last traces 


of lead. The assay should be gradually removed from the | 
furnace to prevent spitting or sprouting. Should the button 
sprout, the assay should be discarded. When the cupel is 
cold the bottom is removed by a pair of pliers, and brushed 
with a stiff brush to remove adhering particles of bone-ash, etc. 
The weight of this button gives the amount of pure silver to 
be taken for the proof- or check-assay if the first method is 
adopted or the weight of bullion to be taken for assay if 


238 A MANUAL OF PRACTICAL ASSAYING. 


the second method is adopted, according to the following 
table ; 


Weight of sheet 


Preliminary Assay of | Silver to be used in Proof, | Bullion to be used for lead to be used, 


500 mgs. gave Ag, mgs. mgs. Volumetric Assay, gms. gms. 
475 480 1.042 5 
450 455 to 460 I.0Q1 7 
425 430 to 435 1.156 8 
400 405 to 410 1,227 10 
375 380 to 385 Le30% II 
350 355 to 360 1.399 12 
325 330 to 335 1.504 13 
300 305 to 310 1.610 15 
250 255 to 260 1.922 07 
200 205 to 210 2.380 19 
150 155 to 160 4.125 20 





First Method.—The check- or proof-assay should not only 
contain very approximately the same amount of silver which 
the bullion contains, but approximately the same amount of 
copper and lead as the bullion. Should the bullion contain 
much gold, the proof should contain gold in the same propor- 
tion. Should the bullion contain much copper, the amount can 
be quickly ascertained by dissolving 0.5 gramme of bullion in 
dilute nitric acid, adding a very slight excess of hydrochloric 
acid to precipitate the silver, filtering off the precipitated silver 
chloride, and washing the precipitate with hot water. The 
filtrate is now rendered alkaline with ammonia, and the copper 
determined by titration with a standard solution of potassium 
cyanide. (See Part II, Chapter XIII.) Or the copper may be 
determined quickly by the colorimetric test. (See Part II, 
Chapter XIII.) In the case of quite fine bullion, as the bullion 
from the cupellation process, the copper can be disregarded. 
The method of making up the proof is best illustrated by an 
example, as follows: Suppose the preliminary assay gave 375 
mgs. of silver and showed the bullion to contain 20 per cent 
copper. The table shows that we would have to weigh out 
from 380 to 385 mgs. of pure silver, and that 11 gms. of lead 
would be required for cupellation. To this should be added 


(ASSAY OF SILVER BULLION. 239 


100 mgs. of pure copper-foil and 25 mgs. of lead. The whole 
is wrapped in the 11 gms. of sheet lead when it is ready for 
cupellation with the regular assay. he reason for making up 
the proof in this manner is that the loss of silver in cupellation 
will depend upon the amount of lead and copper present. 

The pure silver-foil used can be made by the reduction of 
the silver chloride obtained in parting, or it can be purchased 
from dealers. : 

The regular assay is performed as follows: Two portions 
of bullion weighing 0.500 gm. each are accurately weighed out 
on the button-balance and wrapped in the proper amount of 
lead-foil as shown by the table. The lead-foil can be cut into 
sheets of the proper weight. The lead-foil should be free 
from silver; but, if it contains a small amount of silver and its 
silver contents are uniform, the silver which it contains can be 
disregarded, as the same amount will be present in the lead 
used in the proof-assay. The proof is made up as indicated 
above. Have three hot cupels in the muffle and introduce 
into each one of the assays, placing the test-assay in the middle. 
Proceed with the cupellation in the manner described under 
the preliminary assay, taking care to have the cupellation of 
all three of the assays start and finish at about the same time; 
that is, have all three run at about the same temperature. 
Weigh all three buttons: the loss in silver of the test-assay 
will represent the loss in cupellation. In the case of fine 
bullion this loss should be from 4 to 5 mgs. If greater than 
5 mgs.,the assay has been run too hot or too cold. The 
buttons should be bright, and should show no evidence of 
litharge. The loss in the test-assay is added to each of the 
regular assays when the product of the two assays will give the 
fineness of the bullion. The two buttons should not differ 
from each other by more than I mg. A greater difference, 
except in the case of very impure bullion, when a greater num- 
ber of assays should be run, should not be allowed. Suppose 
button No. 1 weighs 489 mgs., button No. 2 weighs 488 mgs., 
and the test shows a loss of 4.5 mgs.; then 


(489 + 4-5) + (488 + 4.5) = 986 fine. 


‘~” 


240 A MANUAL OF PRACTICAL ASSAYING. 


The buttons are parted for gold (see assay of Gold Bullion, 
Part III, Chapter III), and the gold fineness is ded ucted from 
the total fineness (Ag and Au) to determine the silver fineness. 

Second Method.—This method requires the following 
solutions: Normal-salt solution, decinormal-salt solution, and 
decinormal solution of silver nitrate. 

The normal-salt solution is a solution of salt in water, 100 
cc. of which will precipitate exactly 1.0 gm. of silver as silver 
chloride. 

The decinormal-salt solution is a solution of salt in water, one 
cc. of which will precipitate exactly 1.0 mg. of silver. This solu- 
tion is made by diluting one part of the normal solution with 
nine parts of water. In making up this solution care should 
be taken to have the temperature of the solution and the water. 
used for dilution the same. 

The decime-silver solution is a solution of pure silver in 
nitric acid, diluted with distilled water. One cc. of this solu- 
tion contains 1.0 milligramme of silver, consequently I cc. is 
equivalent to I cc. of decime-salt solution. 

To prepare the normal-salt solution dissolve 5.4167 grammes ° 
of pure dry sodium chloride (dried by heating at about 125° C.) 
in distilled water, and dilute to 1000 cc. Where many assays 
are to be made, it is usual to prepare a greater quantity of the 
solution, the above being given simply to indicate the amount 
of salt to be used. In making up and measuring the solutions 
care should be exercised to have the temperatures remain the 
same. A good plan in making up, measuring, and standardiz-. 
ing is to have the solutions at the ordinary temperature of the 
laboratory. The laboratory in which the solutions are kept 
and the assays performed should have a nearly constant tem- 
perature. A convenient form of apparatus in which to keep 
the solutions is a carboy or large glass bottle, provided with a 
rubber stopper perforated with two holes. Into one of these 
holes is introduced a piece of glass tubing whose lower end 
reaches nearly to the bottom of the flask. In the other hole 
introduce a piece of glass tubing bent in the form of a siphon, 
the end in the bottle reaching nearly to the bottom, whilst the 


ASSAY:‘OF SILVER BULLICN, 241 


other end is a foot or so below the level of the bottom of the 
bottle and a convenient height above the work-table. This 
siphon tube should be provided with a stop-cock, situated at a 
convenient height, and a piece of rubber tubing on the end, the 
latter being provided with a pinch-cock. From time to time 
the solution in the bottle should be shaken, and it should be 
restandardized every few weeks, as, no matter what precautions 
are taken, its strength is liable to change. 

The decime-salt solution is prepared by drawing off exactly 
100 cc. of the normal solution and diluting it to 1000 cc. with 
distilled water of the same temperature. It is unnecessary to 
prepare a large quantity of this solution, as it can be readily 
prepared from time to time, as needed, from the normal solu- 
tion. 

The decime-silver solution is prepared by dissolving 1 
gramme of perfectly pure silver in a few cc. of dilute nitric 
acid, and diluting to 1000 cc. It is best to prepare this solu- 
tion freshly about once a week, and it should be kept in a 
ereen-glass bottle covered with black paper, and provided with 
a siphon for convenience in drawing off into the burette. 

After preparing the salt solutions they must be carefully 
standardized as follows: Three or four portions of pure silver 
of exactly I gramme each are weighed out, and each portion 
is introduced into a glass-stoppered flask of about 250 cc. 
capacity. The silver in each flask is now dissolved in Io cc. of 
dilute nitric acid (free from chlorine), placing the flask in an 
inclinea position on the sand-bath to facilitate solution and 
avoid loss. After the silver is all dissolved dilute the contents 
of the flask with about 80 cc. of distilled water. Run intoa 
pipette too cc. of the normal solution, and add the solution 
from the pipette to the contents of the flask. Close the flask 
with the stopper, and agitate violently. After agitation place 
the flask in a dark place (a box with several holes in the top 
in which to introduce the flasks is convenient), and allow the 
precipitate to settle. Repeat the agitation, if necessary, until 
the solution settles clear, and then add I cc. of the decime-salt 
(prepared for this purpose by drawing off 25 cc. of the normal- 


242 A MANUAL OF PRACTICAL ASSAYING. 


salt solution, and diluting with 225 cc. of distilled water) solu- 
tion from a burette. Should a precipitate appear, agitate and 
allow to settle as before, and repeat the addition of decime-salt 
solution until a precipitate fails to appear. The solution should 
be added slowly at first, and the addition stopped as soon as a 
precipitate fails to appear. The reading of the burette is now 
noted, the contents of the flask agitated and allowed to settle. 
The decime solution of silver nitrate is now added from a 
burette, adding not more than I cc. ata time. This addition 
is continued, agitating, and allowing the contents of the flask 
to settle after each addition until the silver nitrate no longer 
produces a precipitate, when the reading of the burette is 
noted. 

The method of calculation is best illustrated by the follow- 
ing examples: 

Suppose 100 cc. of the normal solution was insufficient to 
precipitate all the silver, and 7 cc. of the decime-salt solution 
were added. Thent cc. of the decime-silver solution is added, 
resulting in the formation of a precipitate. The addition ofa 
second cc. of the silver solution fails to produce a precipitate. 
Hence, 100.7 — (.2 — .1) = 100.6 cc. of the normal-salt solution, 
which is necessary to precipitate 1 gramme of silver, whilst only 
100 cc. should be required. The normal-salt solution is conse- 
quently too weak, and the quantity of salt to be added to 1000 
cc. may be calculated as follows: 


(100 — 0.6) 195.4107 20.0% a 
# = 0.0327 grammes of NaCl. 


Suppose 100 cc. of the normal- and I cc. of the decime-salt 
solution were added, the decime solution failing to produce a 
precipitate. Decime-silver solution was then added to the 
amount of 8 cc., the last cc. failing to produce a precipitate. 
Hence, 100.1 — (.8 — .1) =99.4 cc. required to preciaian am 
eramme of silver, whilst 100 cc. should be required’ conse- 
quently the solution contains an excess of salt. 


I ¢ 0.000 “Salto yeeay 
# = salt in excess = 0.0325002 gm. 


ASSAY Uf SILVER SOULLION, 243 


The following calculation gives the number of cc. of water 
to add to each 1000 cc. of solution in order to make it normal: 


0.0325002 


—— 


5.4167 





PL OOO —=1 OFLC, 


Salt or water should be added as required, the solution 
being thoroughly mixed and restandardized. This operation 
is to be repeated until the solution is brought to the normal 
point. After a normal solution is obtained a decime solution 
can be made by diluting 100 cc. of the normal solution with 
goo cc. of water. 

The use of a normal solution of sodium bromide, rather 
than sodium chloride, is preferred by some chemists using this 
method. Sodium bromide is preferable, as silver bromide is 
practically insoluble in water containing a slight excess of 
sodium bromide, whilst silver chloride is slightly soluble in 
water containing a slight excess of sodium chloride. If sodium 
bromide is used, 9.5370 grammes of the dried salt dissolved 
in water and diluted to 1000 cc. should produce a normal 
solution. The solution is standardized, and the assay per- 
formed in the same manner as when sodium chloride is used. 

The regular assay can now be made as follows: First deter- 
‘mine the approximate fineness of the bullion by cupellation, as 
described above, or by weighing out 0.5 gramme of the bullion, 
solution in dilute nitric acid, and titration with the standard 
salt solution, using the normal solution to start with, and the 
decime solution to finish with. A good plan is to pour off one 
half of the solution of the bullion into a beaker, and approxi- 
mately determine the amount of silver in the half remaining in 
the flask. Now add the solution in the beaker to the flask, 
and finish the titration. In this manner the amount of normal- 
salt solution which can be safely added is determined, and the 
final titration with the decime solution is quickly proceeded 
with. 

Having determined the fineness approximately, the amount 
of bullion to weigh out for assay (so as to have about I gramme 


244 A MANUAL OF PRACTICAL ASSAYING. 


of silver present in each assay) can be obtained from the table. 
It is usual to take at least two portions for assay. Dissolve 
each portion in a 250-cc. stoppered flask with dilute c. p. nitric 
acid, and dilute with water to about 80 cc. Add 100 cc. of 
normal-salt solution, agitate, and proceed as above described. 
The method of calculating results is best illustrated by an 
example, as follows: Suppose we have taken I.o1 gramme of. 
bullion, and have used 100 cc. of the normal- and II cc. of the 
decime-salt solution. Having added too much salt solution, we 
add 2 cc. of the decime-silver solution, and titrate again with 
the decime-salt solution, drop by drop, using 0.5 cc. altogether, 
when a precipitate fails to appear. 


Salt solution used, 100 cc. normal, = 1000.00 mgs. Ag. 
4 s “11.5 ce. decime, © (==) ia oa 





IOII.50 mgs. Ag. 
Less decime-silver solution used, 2 cc., = 2.00: hams 





1009.50 mgs. Ag, 
If « = fineness in thousandths, we have 


L012 1000 5sc ss LOOO met. 
+ = 999-5: 


As this assay cannot be made in a laboratory where fumes 
ot chlorine, bromine, or ammonia are present, it is best to have 
a separate room for this assay. If a separate room is used it is 
preferable to have the light admitted through yellow glass, as 
the rays admitted by yellow glass do not decompose chloride 
or nitrate of silver. Should the bullion treated contain mer- 
cury, sunlight will not blacken the precipitated silver chloride. 
Sheuld mercury be present, it may be held in solution by the 
addition of 10 grammes of sodium acetate containing a few 
drops of free acetic acid. 

Should the bullion contain lead, it can be precipitated, before 
titration with the salt solution, by the addition of a few cc. of 
sulphuric acid. 


) “glia ihe lites 


ASSAY OF SILVER BULLION. 245 


Third Method.—Volhard’s method gives excellent results 
on bullion free from copper, but cannot be used for the 
determination of silver in coin or bullion containing even small 
amounts of copper. It consists in dissolving the bullion in a 
small amount of nitric acid, as in the second method, adding 
about 5 cc. of a strong solution of ferric ammonium sulphate 
as an indicator, and titrating with a standard solution of 
potassium sulphocyanide in the manner described in Part II, 
Chapter X, page 145. It is best to prepare two standard 
solutions of potassium sulphocyanide—one where each cc. is 
equivalent to 10 mgs. of silver, and a decime solution each cc. 
of which is equal to 1 mg. of silver. The titration is com- 
menced with the strong solution, and is finished with the 
decime solution. 

The normal solution may be prepared by adding about 9 
grammes of potassium sulphocyanide to the litre of distilled 

' water. 

The author has frequently used this method for the 
determination of the fineness of Doré bullion, produced by 
zinc desilverization and cupellation, and for such material 
considers it as rapid and accurate as any method which we 
have. 





CHAR RE Reis 


THE ASSAY OF GOLD BULLION. 


THE process of assaying, which is essentially one of refining, 
requires the removal of both the base metals and the silver. 
To effect this two operations are necessary : 

First. The base metals are removed by cupellation. Weigh 
out 0.500 gm. on a delicate balance, wrap in 5 gms. of pure 
sheet lead, and cupel (see Chapter II: Assay of Silver Bullion). 
Lead under the action of the heat and air forms litharge, 
which dissolves the oxides of the base metals and carries them 
into the cupel, leaving behind, when the operation is completed, 
which is shown by the brightening of the button, pure silver 
and gold. The button of silver and gold is weighed, and the 
difference between this weight and the 0.500 gm. taken rep- 
resents the weight of the base metal. 

Second. The silver is removed from the gold by solutior 
in nitric acid, the gold remaining behind in an insoluble state. 
In order that the silver be entirely removed, it is necessary 
that there be present at least twice as much silver as gold. 
A preliminary assay is run by weighing out 0.500 gm. of 
bullion, adding 1.0 gm. of pure silver,* wrapping in 5 gms. of 
sheet lead, and cupelling. The resulting button is detached 
from the cupel, brushed and weighed, and then flattened out 
under a hammer, the weight being noted. It is then heated to 
redness in a clay annealing-cup and passed through a small set 
of rolls, which draw it out to about 4 inches in length. It is 
again annealed, and when cold is rolled into a spiral coil called 
a cornet. It is now ready for the acid. For this purpose a 
platinum dish about 3 inches in diameter and 2 inches deep 


* Unless the bullion contains copper about 10 mgs. of pure copper is also 
added to toughen the cornet. 





246 


Dae Ra oOALY OM GOLDY AULLION. 247 


is used. This is nearly filled with c. p. nitric acid of 32° 
Baumé and heated to boiling. The cornets are placed in a 
small platinum crate, with a separate compartment for each 
cornet. This crate is. now lowered into the boiling acid and 
allowed to boil for 10 minutes, as shown by an electric indi- 
cator. The acid is now poured off, the dish filled with fresh 
acid of the same strength, and again boiled for 10 minutes. 
The crate containing the cornets is now lifted out and washed 
with pure distilled water. After drying slowly, the platinum 
crate and cornets are exposed for a few minutes to a strong 
red heat, which condenses and anneals them. When cool, the 
cornets are weighed and the number of milligrammes which 
they weigh is noted. Suppose this preliminary assay shows 
0.380 gm. of gold and o.o10 em. of silver, then twice 0.380 = 
0.700, and 0.760 — 5 (half the silver present) = 0.755 gm. of 
silver, which it is necessary to add to the regular assay in order 
that there be twice as much silver present as gold. 

For the regular assay 0.500 gm. of bullion is weighed out 
on a delicate balance. This weight is marked Iooo. All the 
lesser weights used are decimal divisions of this weight, down 
to one ten-thousandth part. From the preliminary assay the 
amount of silver necessary to add is calculated. The bullion 
and the added silver are wrapped in 5 gms. of sheet lead and 
cupelled, the regular assay being performed exactly as above. 
In practice it is not general to take as much care with the 
preliminary assay as with the regular assay. 

As the process is subject to error from a number of causes, 
but principally owing to the losses of the precious metals from 
volatilization and absorption while on the cupel, and from im- 
perfect extraction of the silver by the acid, it is necessary to 
make a test assay with each set of assays. This assay is made 
from chemically pure gold, and is made up as nearly like the 
bullion under examination as possible. This is passed through 
the same processes as the samples of bullion under assay, and 
side by side with them. It is evident that, if the process were 
a perfect one, we would recover from the test-assay exactly the 
amount of gold taken. If, however, from any cause, it is found 


248 A MANUAL OF PRACTICAL ASSAYING. 


to differ from the weight taken, and therefore found to require. 


a correction, it is assumed that the same correction should be 
made to the regular assays; and this is done. The weights of 
the cornets with this correction give the true fineness in gold. 

The gold fineness being known, and also the fineness in 
silver and gold, the silver fineness is determined by difference. 
In practice the fineness of unparted, or Doré, bars is reported 
to the half-thousandth. 

While the method as described is essentially that adopted 
by some of the government offices, in practice the author uses 
the following modifications: 

A preliminary assay is seldom necessary, as after considera- 
ble experience the assayer will be able to judge very approxi- 
mately the fineness of the bullion by simple eye inspection, 
and from the manner in which the bullion cuts with the shears 
after rolling into a ribbon. These estimates are generally suf- 


ficiently close where two and one half parts of silver (to one. 


part gold) are used in alloying. Where the proportion of two 
to one is adopted a preliminary assay is necessary, as in this 


case so wide a variation is not permissible. For this reason. 


the author has adopted the proportion of two and a half parts 
silver in alloying. 

As the proportion of silver to gold is increased the strength 
of the first acid must be decreased. Where the proportion 
of two and one half is adopted the first acid should have a 
strength of 25° Baumé (= 1.20 sp. gr.). The cornets are boiled 
in this acid until all action of the acid has ceased. This gen- 
erally requires about ten minutes’ boiling. The acid is now 
poured off, and fresh acid of 32° Baumé (= 1.27 sp. gr.) is 
added. The cornets are boiled in the second acid for exactly 
Fen amin utes. ig 

Where a proof or blank assay is run with each set of assays. 
(the use of a proof has been generally adopted) care should 
be exercised that the proof is run under exactly the same con- 
ditions as the bullion under examination. For this reason the 
platinum parting apparatus is preferable to the flasks. Care 


THE ASSAY OF GOLD BULLION. 249 


should also be exercised to have each cornet of exactly the 
same thickness after passing through the rolls. 

As the surcharge of silver (silver remaining with the gold 
after parting) depends upon the thickness of the cornets, the 
strength of the first and second acids and the time of boiling, 
the proportions of alloy, the strength of acid, the thickness of 
cornets, and time of boiling should be the same in all assays. 

The correction for the loss of silver in cupellation of the 
base-metal assay is generally made by running a proof assay, 
the proof being made up of pure gold and silver, and as nearly 
like the bullion under examination as possible (see the fire- 
assay of silver bullion, Part III, Chapter II). Where gas fur- 
naces are used for cupelling the temperature can be controlled 
within quite narrow limits. In such a case the silver losses 
may be determined on bullion of different fineness, and corre- 
sponding corrections can be made in subsequent assays. 

The following table gives the proportions of silver and lead 
used by the author for the gold determination on the average 
bullion carrying silver, and on coppery bullion such as jewellers’ 
melts: 


Ordinary Bullion. ~ Coppery Bullion. 
f a Sitwer ; . Add Lead to 
Fineness. Ad Mae me oe Fineness. By pee Cees fees 
500 400 5 500 550-600 10 10 
550 500 5 550 650-700 9 9 
600 575 5 600 700-750 8 8 
650 650 5 650 750-800 8 8 
700 750 5 700 850 7 7 
750 850 5 750 950 # ‘i 
800 925 44 800 1000 6 6 
850 1025 44 850 1050 6 6 
goo I 100 4 goo I125 5 54 
950 1175 4 950 1200 44 5 
1000 1250 4 1000 1250 4 4 





For the base-metal assay of ordinary bullion 5 gms. of lead is used. 


CHAPTER AV. 


SPECIAL METHOD FOR THE DETERMINATION OF SILVER 
AND GOLD IN COPPER MATTES? EG, 


IN the determination of silver and gold in copper mattes, 
pig-copper, and ores carrying much copper, by the usual method 
of scorification-assay the losses of silver and gold are quite 
large, usually from 2 to 4 per cent of the silver present being 
lost, owing to the fact that in order to obtain lead buttons 
which are soft and free from copper repeated scorifications are 
necessary, and, moreover, it is impossible to obtain lead but- 
tons which are entirely free from copper. If the lead button 
contains copper, silver will be carried into the cupel when the 
button is cupelled. 

The following method is a modification of the method of 
Prof. Whitehead,* and is believed to give the best results: + 

One A. T. of material is introduced into a No. § beaker and 
100 cc. of distilled water are added, stirring the mass with a 
glass rod; 50 cc. of nitric acid (sp. gr. 1.42) are added, and the 
solution is allowed to stand until the action of the acid has 
apparently ceased. Then 50 cc. more acid is added, and the 
solution is allowed to stand in a warm place until the red fumes 
are driven off; the solution is now diluted with distilled water 
to 500 cc., and allowed to stand for several hours. The solu- 
tion is now filtered off through a rather heavy 44-inch filter- 
paper, the water used in transferring the precipitate to the filter 
being usually sufficient to remove the copper and silver salts. 
To the clear solution normal sodium-chloride solution (1 cc. = 
Io mgms. silver) is now added in slight excess. A large excess 

* Journal of Analytical and Applied Chemistry, Vol. VI, p. 262. 
¢ Dr. Le Doux’s paper on the Assay of Copper and Copper Mattes. Results 


and Discussion. Trans. of the Am. Inst. of Mining Engineers, 1894 and 1895. 
250 


——— 


SILVER AND GOLD IN COPPER MATTES, ETC. 251 


is to be avoided, as silver chloride is soluble in an excess of 
salt. The solution is stirred and Io cc. of a saturated solution 
of lead acetate are added, with stirring of the solution. Then 
2 cc. of sulphuric acid (1 part acid to I part water) are added, 
and after stirring the solution is allowed to stand for a few 
hours. When the precipitate has settled the solution is filtered 
off and the precipitate is washed into the filter, finally washing 
the precipitate to remove copper salts. The filtrate should be 
perfectly clear. The filters are removed from the funnels, and 
after wrapping them around the precipitates, are placed in 24- 
inch scorifiers and dried by placing the scorifiers on a hot plate. 
When dry the papers are burned by placing the scorifiers in 
front of the muffle, the scorifiers finally being pushed back 
into the muffle to destroy all the carbon and sulphur. To 
scorifier, containing the gold residue and the silver-lead pre- 
cipitate, is added 5 gms. of litharge, 15 to 20 gms. of test-lead, 
and 1 gm. of borax glass. The charges are now scorified at a 
moderate temperature, and when the scorifications are finished 
are poured. The lead buttons, which should weigh from 6 to 
8 gms. each, are cupelled so as to show feather litharge, and 
the gold-silver buttons are weighed. The buttons are then 
flattened and parted for gold in the usual manner. The assay 
is usually run in duplicate, and the two results should agree 
almost exactly. 

This method may also be used to advantage for the 
determination of gold and silver in base ores, as gray copper, 
arsenical sulphides, etc. The method may also be used for the 
assay of silver sulphides and, in the opinion of the author, is 
preferable to that described on page 252.* 





* Trans. of the Am. Inst. of Mining Engineers, 1895. 


CHAPTER V. 
ASSAY OF SILVER SULPHIDES. 


IN the ordinary crucible-assay of precipitated silver sul. 
phides from a leaching-works the loss of silver in the slag and 
in the cupel will vary from 0.2 to 1.5 percent. There is also an 
additional loss by volatilization during fusion and cupellation.* 
The loss in scorification will vary from 0.8 to I.5 per cent, in 
addition to the usual loss by volatilization. These losses were 
determined in the case of high-grade (11,000 to 12,000 ounces 
silver per ton) sulphides. In the case of low-grade sulphides 
carrying considerable copper the losses will be greater. Scori- 
fication-assay gives the best results. 

In consequence of this loss it is usual to determine the 
silver in these sulphides by “corrected assay.” From six to 
twenty scorification-charges are run on each lot of sulphides, 
using the following charge: Sulphides, 0.1 A. T., test-lead 55 
gms., and borax-glass 5 gms. The lead buttons are extracted 
from the slag, which is retained, and cupelled separately. The 
silver buttons are weighed and their average taken as the 
result, the cupels being retained. 

The slag is pulverized, passed through a 20-mesh screen, and 
assayed by crucible-assay using the following charge: Slag; 
litharge 20 gms.; sodium carbonate, 15 gms.; argol, 2 gms.; 
salt cover. The resulting lead buttons are cupelled, the silver 
buttons are weighed and their average is taken. 

The cupels are pulverized, passed through a 30-mesh screen 





* Transactions of the American Institute of Mining Engineers, Vol. XVI, 
page 378. 
252 


MSsaV OF SILVER SULPAIDES. 253 


and assayed by crucible-assay using the following charge: 
Cupel; litharge, 30 gms.; borax-glass, 30 gms.; sodium carbon- 
ate, 30 gms.; argol, 2 gms.; salt cover. The resulting lead 
buttons are cupelled, the silver buttons being weighed and their 
average taken. 

The average amount of silver recovered from the slag and 
cupel in this manner is added to the average amount obtained 
by the first scorification-assay, the result being the corrected 
assay. 

The gold is determined by treating from 1 A. T.to 4A. T., 
in a beaker, with nitric acid, and proceeding in the manner 
described in Part III, Chapter IV. 


CHARTER SVE 
‘CHLORINATION-ASSAY OF SILVER ORES. 


IN milling silver ores by the Pan-Amalgamation process 
chlorination-assays are made daily to determine the per cent 
of chloride of silver in the pulp. These assays are also made 
as a check on the process in a leaching-works. 

The process requires asolution of hyposulphite of soda con- 
taining two pounds of hyposulphite to the gallon of water, and 
a solution of sodium sulphide. 

Weigh out two samples of the chloridized pulp of from +5 
A. T.to4A. T., according to the grade of the ore. Scorify 
one with about 30 gms. of test-lead for every 71, A. T. taken, 
and cupel. Place the second sample in a beaker and add some 
of the hyposulphite solution. _Warm, and decant on a filter. 
Continue to wash with the hyposulphite, finally washing the 
contents of the beaker onto the filter, until all the chloride of 
silver has been dissolved and leached out of the pulp. This 
can be determined by testing the filtrate from time to time with 
a drop of the sodium-sulphide solution. Whena black precipi- 
tate or brown coloration no longer forms, the silver chloride is 
all dissolved and the desired point is reached. Wash the pulp 
on the filter with warm water, dry, and burn the filter and its 
contents in a scorifier in the muffle. Mixthe ashes with 30 gms, 
of test lead (for each 74, A. T. taken) and scorify. Cupel the 
resulting lead button. Having the assay of the pulp before 
and after leaching, the percentage of chlorination is arrived at 
as follows: 

Pulp-assays before leaching....... 95.00 oz. Ag. 
Pulp-assays after leaching ........ 9.00 oz. Ag. 
254 


CHLORINATION-ASSAY OF SILVER ORES. 255 


Hence, if x = per cent of silver chloride, 


95:(95 —9):: 100: 4. 
+ = 90.5. 


If the pulp contains sulphate of silver, the per cent of sul 
phate present can be determined by weighing out a third sample 


and leaching it with warm water until all the silver sulphate is 


dissolved. Dry, burn, scorify,and cupel the residue. A calcu. 
lation similar to the above will give the percentage of silver - 
present as sulphate. To determine the percentage present as 
chloride deduct this per cent of sulphate from the per cent 
obtained by leaching with the hyposulphite solution. 

To determine the per cent of silver which will be extracted 
by the Russel Process of Lixiviation, see Trans. of the Ameri- 
can Institute of Mining Engineers, Vol. XVI, pages 368-381. 
Also, “ The Lixiviation of Silver Ores,” by C. A. Stetafeldt 
(Scientific Pub. Co.). 


CHAPTER SVIL 
CHLORINATION-ASSAY OF GOLD ORES. 


A CHLORINATION-ASSAY of a gold ore is made to determine 
the probable percentage of gold which may be extracted by 
the chlorination process. 

The percentage of extraction will depend not only upon 
the per cent of free gold present, but also upon the fineness to 
to which the ore is pulverized, the amount of chlorine gas gen- 
erated per ore charge, and the time of agitation. Hence in 
treating a new ore a series of tests under different conditions 
will be required. 

The general practice in a chlorination-mill is to pulverize 
the ore to about 4o mesh, and treat in a closed vessel with 
bleaching-powder and sulphuric acid. The sulphuric acid re- 
acts upon the bleaching-powder and chlorine gas and calcium 
sulphate are produced. (See Part III, Chapter XIV.) The 
amount of bleaching-powder used per ton of ore in the mill 
will vary from about 10 pounds to 60 pounds. The amount of 
sulphuric acid (66° Baumé) used will vary from about 15 pounds 
to 70 pounds per ton of ore. The same ratios should be pre- 
served in the laboratory tests. ) 

A convenient piece of apparatus for the laboratory test is 
a glass-stoppered bottle holding from one to three gallons. 
From one to ten pounds of the ore is weighed out and intro- 
duced into the bottle. The proper amount of warm water is 
added, the contents of the bottle agitated, and the proper 
quantity of bleaching-powder is added. The proper quantity 
of sulphuric acid is now added, the bottle is tightly stoppered, 
and its contents agitated from four to eight hours. It is gen- 
erally best to add a portion of the bleaching-powder and 
sulphuric acid at first, agitate for from three to five hours, and 
then add the balance. In‘order to insure perfect chlorination 

256 


CHLORINATION-ASSAY OF GOLD ORES. 267 


there should always be free chlorine present at the last of the 
operation. This may be determined by removing the stopper 
and holding a bottle of ammonia-water to the mouth of the 
bottle. If free chlorine is present the characteristic fumes of 
ammonium chloride will be produced. 

The pulp is now ready for filtration and washing, which is 
performed in the usual way. When the washings no longer 
give a reaction for chlorine, upon testing with silver-nitrate 
solution, the washing is finished. The pulp is, now dried, 
sampled, and assayed for gold in the usual way. 

Having the assay on the ore before and after treatment, 
the following gives the percentage of extraction: Suppose the 
ore before treatment assayed 0.77 oz. Au, and after treatment 
0.04 oz. Au per ton of 2000 pounds. Then 


ee 0,04 0.73 = gold extracted, and 0.77:0.73 :: 1003243 
t= O4.6 — percentage of extraction. 


Sulphides must be roasted previous to treatment. The 
roasting must be carefully conducted, and the ore finally 
brought to a dead-roast, in order to insure a good percentage 
of extraction. The roasted ore should not show much gver 
0.3 per cent of sulphur. 

The following table gives the amount in grammes of bivach- 
ing-powder or sulphuric acid which correspond to the pounds 
per ton used in the mill: 


_ 3.4 gms. to I lb. is equivalent to 15 lbs. per toy, 


4.54 66 66 66 66 66 66 20 66 66 6 
5.67 6c 66 6é 66 6¢ 66 25 66 6¢ & 
6.80 66 66 66 66 66 6c 30 66 66 66 
7.04 66 66 66 66 66 66 35 66 66 66 
9.07 66 66 6¢ 66 66 66 40 66 6é 66 
TO.21 6é 66 (t9 66 6¢ 66 45 66 rf] 6é 
I 1.34 66 66 66 66 66 66 50 66 6 66 
£2.37 66 66 66 66 6é 66 55 66 6 6e 
WG! 66 66 6¢ 66 6é 66 60 66 6 66 
14.74 66 66 66 66 66 66 65 66 6; c¢ 


15 88 és 66 66 66 66 66 70 66 6) 66 


CHAPTER® Vill. 


ASSAY OF GOLD AND SILVER ORES CONTAINING 
METALLIC SCALES. 


IF an ore of gold or silver contains coarse metallic particles 
the sample will consist of pulp which has passed through the 
sieve and of metallic scales which remain on the sieve. 

The pulp is weighed (preferably in grammes) and its assay 
value in gold and silver determined in the regular manner, 
either by scorification or crucible-assay. The scales are also 
weighed (preferably in grammes) and their assay value in gold 
and silver is determined by scorification- or crucible-assay. 
If the sample of scales is not large, the whole is taken for assay. 
If too large, an aliquot portion is carefully taken from the 
sample for assay. 

The results may be calculated in the same manner as in the 
assay of base bullion (see Part III, Chap. I), or they may be 
calculated by the following formula :* 

Let A = the weight of the pulp in grammes; 

£4 = the weight of the scales in grammes; 

C = the assay value of the pulp in ounces of gold or 
silver per ton of 2000 pounds; 

D = the total number of milligrammes of gold or silver 
in the scales. 





Now aa = the number of assay-tons in the pulp; and - 
AC Fal : 
= the number of milligrammes of gold or silver in the 
29.166 


pulp. 


* State School of Mines Scientific Quarterly, Vol. I, No. 2, Sept. 1892. 
258 


ASSAY OF GOLD AND SILVER ORES. 259 


Hence, aa + D =the number of milligrammes of gold 


or silver in the whole sample. 

Now if we divide the total number of milligrammes of gold 
or silver in the whole sample by the total number of assay-tons 
in the whole sample, we will have the assay value of the whole 
sample in ounces per ton of 2000 pounds. The expresssion 
A+B 
29.106 
_ sample. Hence, making the division, we obtain the following 
formula for the assay value of the whole sample: 


equals the total number of assay-tons in the whole 


AC + 29.166D 
ATS Ree 


EXAMPLE.—Suppose the pulp weighed 105.23 gms. The 
scales weighed 8.135 gms. One A.T. of the pulp yielded 10.5 
mgs. of Ag and 28.3 mgs. Au. One gramme of the scales upon 
assay yielded 215.5 mgs. Ag -and 682.5 mgs. Au. Now the 
total number of milligrammes of Ag in the scales equals 


SoS G21 5650) Ces 
I = 1753.09 = D; 


and 


105.23 X 10.5 + 29.166 X 1753.09 


Sere 
(et eee 460.77 ozs. Ag per ton 


In like manner we obtain for the assay value of the sample 
in gold per ton 1454.68 ounces. 


CHAPTER IX. 
AMALGAMATION-ASSAY, 


THE amalgamation-assay of gold and silver ores is some 
times made to determine the probable per cent of the gold and 
silver in the ore which can be extracted by amalgamation. Like 
all laboratory tests, where only small quantities can be taken, 
the results will simply serve as a guide to show what may 
probably be expected on a commercial scale in the mill. 

Gold Ores.—Pulverize about three pounds of the ore and 
pass through an 80-mesh sieve. Sample carefully and assay the 
sample. Weigh out from one to three pounds of the pulverized 
ore and wash by panning in the gold pan. The ordinary gold 
pan is a shallow sheet-iron pan 15 inches in diameter across 
the top, I1 inches in diameter on the bottom, and 2 inches 
high. The ore is placed in the pan with water, and panned 
by giving the pan a vibratory motion as in vanning, the 
light particles being washed over the sides. An expert panner 
usually performs the operation under water. When all the 
light particles of gangue have been washed off, leaving only 
the gold and heavy material (as black sand) in the pan, the 
contents of the pan are washed into a wide-necked flask or 
bottle and a few ounces of mercury added. A cork or stopper 
is fitted in the neck of the flask and the contents agitated. 
It is best to use boiling water in the flask, as heat assists 
the amalgamation. The pulp and mercury in the flask are 
agitated several times when the contents of the flasks are 
poured off, except the mercury and amalgam, and washed 
several times with water. The contents of the flask are finally 
washed out into the gold pan and the mercury and amalgam 


further freed from particles. of ore by panning. The clean 
260 





AMALGAMATION-ASSA Y. 261 


mercury and amalgam are now strained through a clean, tight 
piece of buckskin, when the amalgam will be left behind in the 
skin, the mercury passing through. This amalgam is collected 
in a small porcelain crucible and heated, gradually at first, to 
drive off the mercury, finally heating to redness. It is now 
cooled, wrapped in a piece of sheet lead, cupelled, and the re- 
sulting button weighed. The weighed button is alloyed with 
silver, and parted as in the assay of gold bullion. (See Part 
III, Chapter III.) 

The calculation of results is as follows: Suppose the ore 
assayed 1.0 oz. gold and 2 oz. silver per ton. The button 
from amalgamation weighed 18 milligrammes. After parting, 
the button of gold weighed 12 milligrammes. Hence the button 
contained 6 milligrammes of silver. As we saved 12 mgs. of 
gold and 6 mgs. of silver from one pound, we would have saved 
24 grammes of gold and 12 grammes of silver if one ton of ore 
were used. As there are 31.1035 grammes in one ounce Troy, 
we have 





ae = 0.7716 oz. of gold saved per ton, 
and 

2 0.3858 oz. of silver saved per ton. 

31.1035 


Let x = per cent of gold saved and y = per cent of silver 
saved. Then 


ONO. 7710-22 100 2.8%, =. 7 7-107: 


Ora or 100: 7.0 =a10,20%- 


Silver Ores.—From one to three pounds of the ore are 
pulverized, sampled, and assayed as before. One to three 
pounds are weighed out and placed in a small laboratory 
srinding-pan together with hot water. The pulp in the pan is 
then ground from one to three hours. As copper sulphate 
and salt frequently assist the amalgamation on some ores, they 
can be added in from 0.5 to 5.0 grammes of each. A few 


262 A MANUAL OF PRACTICAL ASSAYING, 


ounces of mercury (according to the amount of silver in the 
ore) are added with the pulp. After the grinding is finished 
the contents of the pan are agitated with water and the pulp 
drawn off, the final washing being performed in the gold pan 
as before described. The amalgam is collected and treated as 
before, the calculations being as above. 

Another method, and the one which the writer prefers, is 
to have a small pan, similar to the gold pan but only about 8 
inches in diameter, made from sheet copper. The bottom and 
sides of this pan are then covered with a coating of amalgam. 
A few ounces of the finely pulverized ore are introduced into 
the pan, the mass thinned with water, and the pulp thoroughly 
stirred from I to 3 hours with a wooden stick rounded on the 
end, so as to bring all particles of the pulp in contact with the 
amalgamated surface of the pan. The pulp is now poured off 
on to a filter, and all the pulp remaining in the pan washed 
on to the filter with the aid of a wash-bottle. The filter and 
its contents having been thoroughly dried, the pulp is sampled 
and assayed. The difference between the original assay of the 
ore and the assay of the tailings will be the silver and gold 
which has been collected by the amalgamated surface of the 
pan, or the silver and gold in the ore which can be saved by 
amalgamation. Copper pans the same size and shape as the 
gold pan can also be obtained. It is only necessary to amal- 
gamate the sides of the pan fora short distance above the 
bottom. 


CU AU a by Oa ee 92 
ANALYSIS OF COAL AND COKE, 


MINERAL coal is made up of different kinds of hydrocar- 
bons, with, perhaps, in some cases, free carbon.* Mineral 
coals may be classified as follows, according to H. M. 


hance = 


Anthracite—Volatile matter is usually lessthan 7p.c. 
Semi-anthracite “ pe areal fone pF ahs TO 
Semi-bituminous “ es ae Fi ae Looe 
Bituminous—Volatile matter is usually more than 18 “ 


To this classification should be added the lignites, or brown 
coals, which carry a high percentage of water, and in which the 
percentage of volatile matter is always greater than 18. 

For practical purposes, an approximate analysis, which 
consists in the determination of moisture, volatile combustible 
matter, fixed carbon, sulphur, and ash, is all that is required. 
In the analysis of coke all that is usually required is the mois- 
ture, ash, and sulphur. 

Approximate Analysis.— Determination of the Motsture.— 
One gramme of finely pulverized coal is introduced into a 
previously weighed platinum crucible and dried in an air-bath 
at a temperature of 115° C., until the weight remains constant 
or begins to increase owing to the incipient oxidation of the 
finely divided iron pyrites. The last lowest weight is taken, 
and the loss equals moisture. 

Determination of the Volatile Matter.—Heat the crucible 
and its contents, after having determined the moisture, over 
the flame of a Bunsen burner, gradually raising the temperature 


* Dana’s System of Mineralogy, Ed. of 1885, p. 754. 
+ Geological Survey of Pennsylvania, 1888. 
263 


264 A MANUAL OF PRACTICAL ASSAYING. 


and keeping the crucible closely covered to avoid loss by finely 
divided particles of carbon being carried off mechanically. 
Continue this heating until all of the light combustible matter 
is expelled. This will require 4 to 5 minutes’ heating. Now 
place the crucible over the flame of a blast-lamp and gradually 
raise the temperature to a bright red, and continue the heat to 
constant weight or until all of the volatile matter is expelled. 
This heating will usually take about 10 minutes, and should be 
carefully conducted in order to avoid loss mechanically, and 
should not be unduly prolonged, as this would involve loss of 
fixed carbon by oxidation. A little experience will teach the 
assayer when the operation is finished, so that not more than 
two or three weighings need be made. Cool the crucible and 
its contents in a desiccator, and weigh. The loss equals volatile 
matter + $ the sulphur. 

Determination of the Fixed Carbon and Ash—Heat the 
crucible and its contents, after having expelled the moisture 
and volatile matter, over the flame of a blast-lamp or in the 
muffle-furnace at a gradually increasing temperature, until all 
of the carbon is oxidized and expelled. It is best to heat for 
half an hour and weigh. Heat for Io minutes and weigh 
again, repeating this operation until the weight remains con- 
stant. After a little experience two weighings will generally 
be sufficient, the second being found to correspond to the 
first. Loss equals fixed carbon and half the sulphur, and the 
final weight, less the known weight of the crucible, equals ash. 

Whilst this analysis is at best an approximation, especially 
as regards the determination of volatile matter and fixed car- 
bon, it will be found that after a little practice it will give a 
very close approximation to the truth, and duplicate analyses 
made on the same sample will agree almost exactly. 

The supposition that half of the sulphur is expelled with the 
volatile matter and that half is expelled with the fixed carbon 
is based upon the supposition that all of it is in the form of 
iron pyrites. Of course this supposition would be almost 
universally wrong, but, however, for practical purposes it 
answers all requirements, especially in a coal low in sulphur. 


ANALY SIS OL >°COAL AND COKE, 265 


In any case the supposition would be wrong, as, should all of 
the sulphur exist in the form of iron pyrites, it is extremely 
improbable that half would be expelled in the treatment given 
to drive off the volatile matter. For practical purposes it may 
generally be considered that half of the sulphur in the form of 
pyrites is driven off with the volatile matter and the other half 
with the fixed carbon. 

If it is necessary to determine the sulphur which exists in 
the coal as calcium sulphate and pyrites, it may be done as 
follows: Determine the total sulphur by heating 2 to 5 
grammes of coal with nitric acid and potassium chlorate, or 
by fusion with caustic potash (see Part II, Chapter II), evap- 
orating to dryness, after addition of hydrochloric acid and 
previous addition of bromine in the case of fusion, boiling with 
water and hydrochloric acid, filtering, washing, and the addi- 
tion of barium chloride to the filtrate. 

The sulphur existing as calcium sulphate may be deter- 
mined by boiling 5 grammes of pulverized coal with a solution 
containing about 5 grammes of c. p. sodium carbonate (free 
from S), thus decomposing the calcium sulphate into sodium 
sulphate and calcium carbonate. Filter the solution, wash 
thoroughly with warm water, acidify the filtrate with hydro- 
chloric acid, and determine sulphur as usual. The difference 
between the total amount of sulphur and the sulphur found 
after boiling with sodium carbonate (S as CaSQ,) represents 
the amount as pyrites. The same process is applicable to the 
determination of iron sulphide and gypsum in coke. 

Any phosphorus which the coal may contain will be in the 
Soupeeltetequired, determine it according to Part II, Chapter 
III. If determined, deduct it from the ash in the report. 

The manner of tabulating and calculating results is best 
illustrated by an example as follows: 


Pe er sana ose ey + whos Pe sieteratetsiscan es 15 
Peeemmatter—- 4 sulphur... 22... <<. 2725 
Timedrearbon —-s sulphur... 2.2% 2 cele + 61.3 
Pe heal Wain’ PHOSPNOFUS, |. %).6) se). tc es oie « Gu 


SARE CATE? pie ie ER RED eas Cy CEE io eon aie 1.0 


266 A MANUAL OF PRACTICAL ASSA YING. 


When the sulphur is determined, if we deduct half from the 
volatile matter and half from the fixed carbon, the report would 
be as follows: 





IMEDISEUIT Cte. es a abies aasrcaee epeiens ee : 1.50 
hy Olatiiermattern wa. F eigen sa et aee oie 27.00 
PUIXCONCALOOUA oot: cee teats civera'e elvis regatta 60.80 
Ash, including phosphorus, . 3. ..../¢. =. aes teeess 
OULD eit testes tee em sree stares stan Joie ae ae 

100.00 


Determination of the Specific Gravity.—The specific gravity 
of a coal is often required. Take a small piece of coal and 
weigh it on the balance, then in water by suspending it from 
the arm of the balance by a hair or thin wire. The piece 
taken should not be too small, and care should be taken that | 
no air-bubbles adhere to it during the weighing. The coal 
also should be thoroughly soaked, which can be attained by 
immersing the lump, after attaching the hair or wire to it, in 
the flask of the filter-pump, and exhausting the air in the 
apparatus. The temperature of the air and water should be 
the same, about 60° F. . 

Let W = the weight of the coal in air ; 

W’ = the weight of the coal in water. 


W 
The specific gravity = Wow" 


Determination of the Heating Power.—This determination 
is sometimes required, but at the most is simply an approxi- 
mation. Knowing the elementary constitution of the fuel, the 
heating power may be tested by determining the amount of 
oxygen required to burn it. Mix 1 gramme of powdered coal 
and 50 grammes of litharge, or white lead when pure, together 
in a clay assay-crucible, and cover with about 20 grammes of 
litharge. Heat in a crucible furnace, with a gradually increas- 
ing heat until the fusion is complete, which will require from 
Io to 15 minutes. Remove the crucible from the fire, pour, 


ANALYSIS OF COAL AND COKE. 267 


and when cold hammer and weigh the lead button. Pure car- 
bon should reduce 34 times its own weight of lead; hydrogen, 
102.7 times its own weight. 

One part of pure carbon can raise the temperature of 8080 
parts of water 1°; consequently, if the fuel is assumed as car- 
bon, its value in heat-units may be estimated by multiplying 
8950 by the weight of the lead button obtained in the assay. 
As hydrogen is always present in the coal this method neces- 
sarily gives low results. 

If an elementary analysis of the coal has been made to de- 
termine its percentage of carbon and hydrogen, the heating 
power can be accurately determined. 

Elementary Analysis.—An estimation of the total carbon 
and hydrogen which the fuel contains may be made as follows: 
The fuel is burned in a stream of oxygen, the. resulting CO, 
and H,O being caught in suitable apparatus and weighed in 
those combinations. The same apparatus as is used for the 
determination of carbonic acid and water in white-lead (see 
Pare tieChap. V, and Part I1I, Chap. XV), may be used with 
slight modifications. Take a piece of combustion-tubing about 
28 inches long, and about one half an inch internal diameter, 
fit to each end corks through which are passed tubes of about 
one-tenth inch internal diameter and 4 inches in length. 
About 2 inches from the front end of the tube (the end to 
be attached tothe apparatus for absorbing CO, and H,O) 
place a plug of asbestos which has been previously ignited to 
remove all moisture and carbonaceous material. Back of 
this plug place enough freshly-ignited CuO to fill the tube a 
little more than half, and push down upon this another plug 
of ignited asbestos. Have at the rear end of the combustion- 
tube two bottles, with corks and tubes, for drying the oxy- 
gen and removing from it any traces of CO, it may contain, by 
bubbling it through the bottles containing, respectively, con- 
centrated H,SO, and strong KOH, having the H,SO, bottle 
next tothe tube. For the front end have a tube filled with 
neutral calcium chloride in fragments, through which a current 
of dry CO, has passed for some time, followed by a current of 


268 A MANUAL OF PRACTICAL ASSAYING. 


dry air. To this attach a U-tube filled with fresh soda-lime . 
for the absorption of the carbonic acid. The coal, from which 
the moisture has been driven off by previous drying, is 
weighed out into a platinum boat. Weigh the calcium 
chloride and the soda-lime tubes. Connect the combustion- 
tube at the rear end with the sulphuric-acid and potassium- 
hydrate bottles, and at the front end with the aspirator, heat 
it to redness, and then draw a current of air through it until 
cool. Now introduce the platinum boat into the rear end of 
the tube, replace the cork and connect the calcium-chloride 
and soda-lime tubes at the front end, connecting the last with 
the aspirator. Draw a slow current of air through the tube, 
and heat the front end of the CuO, carrying the heat gradually 
forward. Arrange it so that the CuO shall be highly heated 
before the coal begins to burn. Just before the heat reaches 
the boat attach the tube from the oxygen cylinder, and force 
a slow current of gas through the tube. Heat the coal 
moderately so that it will burn slowly and not give off the 
gases too rapidly. When the coal is completely consumed, 
disconnect the oxygen cylinder, remove the heat, and draw a 
current of dry air free from carbonic acid through the appa- 
ratus until cool. Detach the tubes and weigh. The increase 
in the weight of the calcium-chloride tube represents water to 
be calculated to H, and the increase in weight of the soda-lime 
tube represents carbon dioxide to be calculated to C. 


iN Ra), 
ANALYSIS OF GASES, 


IN a gas or metallurgical works where a number of analyses 
of mixtures of gases are required daily it is only possible to do 
the work with simple apparatus. 

The following apparatus for the rapid analysis of gases and 
the method of using it were first described by A. H. Elliott in 


the School of Mines Quarterly (Vol. III, No. 1, page 15): 


Whilst this method does not compare with the elaborate 
methods of Bunsen and others, where very delicate readings 
and nice precautions are taken, it gives very good results for 
technical work and answers every purpose in the everyday 
practice of a gas or metallurgical works. 

_ The great advantages of this method are the rapidity with 
which an analysis can be made (about forty-five minutes) and 
the simplicity and inexpensiveness of the necessary apparatus. 

The apparatus is shown in the drawing. The tube 4 is of 
about 125 cc. capacity, whilst 4, although of the same length, 
holds only 100 cc. from the mark VD, or zero, to the mark on 
the capillary tube at C, and is carefully graduated into +, cc. 
The attachments to these tubes below are seen from the draw- 
ing, except that the stop-cock / is three-way, with a delivery 
through its stem. The bottles K and ZL hold about one ‘pint 
each. The tubes A and & are connected with each other and 
with the funnel J/ by capillary tubing about one millimetre in 
internal diameter. There is a stop-cock at G and another at 
F, whilst the funnel J/, holding about 60 cc., is ground to fit 


‘over the end of # above. At £& a piece of rubber tubing 


unites the ends of the capillary tubes, which are ground off 


square to make them fit as closely as possible. 
269 


270 A MANUAL OF PRACTICAL ASSA VYING. 


In beginning the analysis of a mixture of gases, the stem 
exit of the cock / is closed by turning it so that Z and A are 
connected through the rubber tubing; the stop-cocks F and G 
are opened and water is allowed to fill the apparatus from the 
bottles A and ZL, which have been previously supplied. When 
the water rises in the funnel J7, and all air-bubbles have been 


py 
Bee oo 
< HIF 
ed = 
= 


Cg 
(ae 
IC “e 
= 
3 
ieee 
LD 
In or 
= H SR 
UT 


forced out of the tubes, the stop-cocks F and G are closed, the | 
funnel J7 is removed, and the tube delivering the gas to be 
tested is attached in its place. By now lowering the bottle L 
slowly, and simultaneously opening the stop-cock F/, the tube 
A is nearly filled with gas, and the stop-cock / is closed. The 
tube delivering the gas is now removed, the funnel JZ replaced, 
the bottle Z raised, the bottle X lowered, and by opening the 
stop-cock G the gas is transferred to the graduated tube JS. 
By placing the bottle Zon a stand at about the level of the 
water in A, the level in B and in the bottle K can be adjusted 
to the zero point, and the stop-cock G is closed. The excess 
of gas in A is expelled by opening the stop-cock F and raising 


ANALYSIS OF GASES. 271 


the bottle Z. The gas remaining in the capillary tube between 
C and the vertical part is disregarded, or in very careful work 
it may be measured and an allowance made in not filling the 
tube 4 quite to the zero mark, but usually it is too small to be 
worth notice. 

Having measured the gas to be tested, it is now transferred 
by means of the bottles K and Z into the tube A, and the fluid 
chemicals added by placing them in the funnel J7 and allowing 
them to flow down the sides of the tube slowly, being careful 
never to allow the fluids to run below the level of the top of 
the vertical tube in the funnel. It is best to have a mark on 
the outside of the funnel about three quarters of an inch above 
the top of the level of the vertical tube, and never to draw the 
fluid down below this point. 

Having treated the gas with the chemical, it is transferred 
by means of the bottles to the tube 5, to be measured. 
Should the chemical get into the horizontal capillary tube, the 
passage of a little water from the bottle A will remove it, be- 
fore transferring the gas. When the gas residue is in 4, and the 
fluid in A has been adjusted at the mark C on the horizontal 
tube, the stop-cock G is closed, the bottle K is lowered till the 
level of the water in it and that in the tube 4 are the same, 
and the reading is made. The tube 4 is now filled with the 
chemical just used and water. By turning the stem of the 
three-way cock /, so that it communicates with A, and also 
opening the stop-cock /, the contents of the tube can be run 
out, and water run through the funnel J7 to clean the tube for 
a new absorption. When the tube is clean, by turning the 
stop-cock J, so that A and Z communicate, the water is forced 
into A, and the apparatus is ready to receive the gas for new 
treatment. 

By this means the gas is removed from the action of the 
water used to wash out the chemicals, and the chemicals are 
completely removed from any interference with each other 
_ when treating a mixture of gases. 

In using this apparatus the solutions are added in the fol- 


-lowing order: 


272 A MANUAL OF PRACTICAL ASSAYING. 


1. Potassic hydrate, to absorb carbon dioxide (also hydro- 
gen sulphide and sulphurous oxide if present. If these gases 
are present in large quantities special methods are necessary 
for their estimation). 

2. Potassium pyrogallate, to absorb oxygen. 

3. Bromine, to absorb illuminants, like olefiant gas and 
acetylene, and after the absorption is complete, and the 
bromine vapors cause an expansion, a little potassium hydrate 
is added, to absorb these vapors before the gas is transferred 
and measured. 

4. Cuprous chloride in concentrated hydrochloric-acid solu- 
tion, to absorb carbonic oxide. After this absorption is com- 
plete, the gas is transferred to the measuring tube, the con- 
tents of the tube A run out, the tube washed and filled with 
water from the bottle Z. The gas is now transferred to A, 
and treated with potassium-hydrate solution, to absorb hydro- 
chloric-acid vapors, before the final reading is made in B. 

The treatment up to this point takes from twenty to thirty 
minutes, according to the amount of practice the operator has 
had with the apparatus. The gas residue still contains marsh- 
gas, hydrogen, and nitrogen. By removing the funnel J/7 and 
attaching in its place a rubber tube communicating with an 
explosion eudiometer in a deep cylinder of water (both rubber 
tube and eudiometer being drawn full of water), a portion of 
the gas residue can be mixed with oxygen, exploded, and the 
contraction and the carbonic acid determined; the marsh-fas 
and hydrogen being calculated by the usual formula. The 
nitrogen is found by the difference of the addition of the other 
constituents and one hundred. The explosion-tube is a similar 
tube to A, without the lower attachment and the lateral capil- 
lary tube above; the funnel WV being retained, and two plati- 
num wires being fused into the glass near the top, to give the 
spark for ignition. It is only necessary to clamp this tube 
down upon a piece of cork in a vessel of water during explo- 
sion, and adjust the water-level in a tall cylinder of water when 
making the readings of contraction and absorption of carbon 
dioxide. 










_ ANALYSIS OF GASES. 273 
a The water used in the apparatus should be of the same 
_ temperature as the room in which the analysis is made, and 
A j by careful handling little or none of the chemicals used will get 
into the bottle Z. 


=" an 


ay 


_ When working in a warm place the tube B should be sur- 


_ rounded with a water-jacket, to prevent change of volume in 
_ the gas while under treatment. 


CHAPTER XII. 
ANALYSIS OF WATER. 


THE following easy method of analysis will serve for the 
determination of the value of a water for domestic or manu- 
facturing purposes : 

Determination of Total Solids.—Evaporate 500 cc. of 
the water to dryness in a weighed platinum dish. The evapo- 
ration is made either on the water-bath, or the dish may be 
placed upon a piece of asbestos board and evaporated over the 
flame of a Bunsen burner, care being exercised to not allow 
the contents of the dish to boil, as this is liable to result in 
loss. Now heat the dish and its contents in an air-bath at a 
temperature of 110° C. to constant weight. This weight will 
represent the mineral constituents of the water and the organic 
and volatile matter. This weight in milligrammes multiplied 
by o.2 will give the parts in 100,000, and by 0.1166 the grains 
per U. S. gallon of 231 cubic inches. 

Organic and Volatile Matter.—After evaporating and 
weighing as above, heat the dish and its contents at a low-red 
heat until all organic matter is consumed and the contents are 
white or nearly so. Now add about 50 cc. of water saturated 
with carbon dioxide and evaporate on a water-bath, repeat the 
treatment with carbon dioxide, and evaporate again. Dry in 
an air-bath at 110° C. as before, cool, and weigh. The loss in 
weight approximately expresses the amount of volatile and 
organic matter in the quantity of water taken. 

Analysis of Residue.—The residue obtained as above is 
now moistened with a few drops of hydrochloric acid, about 
50 cc. of hot water is added, and the contents of the dish again 

274 


ANALYSIS OF WATER. 275 


evaporated to dryness, and finally heated in an air-bath at 
110° C. until there is no longer any odor of chlorine. It is 
now dissolved in hot water, a few drops of hydrochloric acid 
added, transferred to a small beaker, and boiled for a few min- 
utes. It is now filtered through a small filter, washed with hot 
water, and the insoluble residue dried, ignited, and weighed. 
This weight expresses the amount of silica in the quantity of 
water taken, the results being calculated as above. 

The filtrate from the silica is now boiled for a few minutes, 
with the addition of a few drops of nitric acid, to insure the 
oxidation of any ferrous salt which may be present, and made 
decidedly alkaline with ammonia. It is now boiled to expel 
the excess of ammonia, and the precipitated hydrates of iron 
and alumina are filtered off through a small filter and washed 
until the washings show no reaction for chlorine when tested 
with a solution of silver nitrate and nitric acid. The precipi- 
tate is ignited in a platinum crucible and weighed as Fe,O, 


rand AL-O). 


The filtrate from the iron and alumina is now rendered 
decidedly alkaline with an excess of ammonia, and an excess 
of a solution of ammonium oxalate added. The solution is 
boiled for a few minutes and then allowed to cool; when cold 
it is filtered through a small filter, and the precipitated calcium 
oxalate is washed thoroughly with hot water. In case the 
water contains much magnesia it will be necessary to dissolve 


this precipitate in a little hydrochloric acid and water, and 


reprecipitate with ammonia and ammonium oxalate. (See 
Part II, Chap. XXIII and Chap. XXIV.) The calcium oxa- 
late is then ignited over a Bunsen burner, and finally over a 
blast-lamp to constant weight, and weighed as CaO. The 
results are calculated by the use of the same factors as above. 

The filtrate from the lime is evaporated to about 75 cc., 
cooled, and 5 cc. of hydrodisodic-phosphate solution added. It 
is stirred with a glass rod for a few minutes, avoiding allowing 
the rod to touch the sides of the beaker, and allowed to stand 
several hours in acold place. It is filtered onto a small filter 
and washed, until free from chlorine, with a solution of ammo- 


276 A MANUAL OF PRACTICAL ASSAYING. 


nium nitrate (1 gm. salt in 10 cc. of water). It is dried, 
ignited, and weighed as Mg,P,O,. The weight of the precipi- 
tate in milligrammes multiplied by 0.07206 will give the parts 
by weight of MgO in 100,000 parts of water, and multiplied 
by 0.042 will give the number of grains of MgO in one U.S. 
gallon. 

In the case of a very pure water, it will be necessary to 
take a greater quantity of the water than 500 cc., but in most 
cases a half litre will be sufficient. 

Determination of Alkalies.—From # to 5 litres of water 
are evaporated in a platinum dish to about 1oo cc. The solu- 
tion is acidified slightly with hydrochloric acid; a saturated 
solution of barium hydrate is added until the solution is 
strongly alkaline; the solution is boiled, the precipitate filtered 
off and thoroughly washed with hot water until the washings 
are free from chlorine. To the filtrate ammonium carbonate 
is added as long as a precipitate is produced, the solution is 
boiled, and the precipitated barium carbonate filtered off and 
washed with hot water until the washings no longer give a 
reaction for chlorine. The filtrate is evaporated to dryness, 
and heated at a low-red heat, to burn out the ammonium 
chloride. Take the dry mass up with hot water and repeat 
the treatment with barium hydrate and ammonium carbonate, 
to insure the complete removal of the magnesia which may 
have been held in solution by the alkaline chlorides. Finally, 
evaporate the filtrate to dryness in a weighed platinum dish, 
expel all ammonium chloride present by heating to a low-red 
heat, cool, and weigh the mixed chlorides of potassium and 
sodium. The potassium and sodium may be separated and 
determined as described in Part II, Chapter XXVI. 

The weight of potassium platinic chloride obtained (in 
grammes), multiplied by 0.30557, will give the weight of the 
potassium chloride, which weight subtracted from the weight 
of the mixed chlorides previously obtained will give the weight 
of the sodium chloride. The weight (in milligrammes) of the 
sodium chloride obtained from the treatment of 500 cc. of 
water, multiplied by 0.0788 and 0.1061, will give the. parts of 


ANALYSIS OF WATER. 277 


Na and Na,O, respectively, in 100,000 parts of water. For the 
same conversion of potassium chloride the factors are 0.1049 
and 0.1263. To convert parts in 100,000 into grains per U. S. 
gallon, multiply by 0.583. 

Determination of Sulphuric Acid.—Acidify 500 cc. of 
water with about 5 cc. of hydrochloric acid, and evaporate to 
about 150 cc. Filter, if necessary; boil the solution, and 
whilst boiling add an excess of a hot solution of barium chlo- 
ride. Boil for a few minutes and allow to cool. Filter, wash 
with hot water, dry, ignite, and weigh the BaSO,. The weight 
of this precipitate in milligrammes multiplied by 0.0687 gives 
the number of parts of SO, in 100,000 parts of water, and 
multiplied by 0.04 the number of grains of SO, in one U.S. 
gallon. 

Determination of Chlorine.—The determination of chlo- 
rine is best made volumetrically as follows: Prepare a standard 
solution of silver nitrate by dissolving 4.788 gms. of c. p. crys- 
tallized nitrate of silver in distilled water and diluting to 1000 
cc. Each cubic centimetre of this solution should precipitate 
exactly 1 mg. of chlorine. This solution may be standard- 
ized by means of a dilute solution of pure fused sodium chlo- 
ride. A solution of potassium chromate, made by dissolving 
5 gms, of the pure salt in about 100 cc. of water, is used as an 
indicator. 

To determine the chlorine, transfer 100 cc. of the water to 
be examined to a porcelain evaporating dish, add 2 cc. of the 
indicator solution, and then run in from the burette the stand- 
ard solution of silver nitrate until the red precipitate of chro- 
mate of silver, which is at first decomposed by the excess of 
chlorine, is just permanent. The burette reading will give 
directly the number of parts of chlorine to 100,000 parts of 
water. To convert this into parts in one U.S. gallon multiply 
by 0.583. 

For domestic purposes the amount of organic matter, free 
and albuminoid ammonia which the water contains is very 
important. 

Permanganate Test.—This test is made to determine the 


er Mane ee 
' a 
' 


278 A MANUAL OF PRACTICAL ASSAYING. 


amount of oxidizable organic matter in water, and is claimed 
by some chemists to be quite as valuable as the determination 
of the albuminoid ammonia. The test requires a solution of 
oxalic acid and a solution of potassium permanganate, which 
are prepared as follows: Dissolve 0.7875 gm. of pure crystal- 
lized oxalic acid in 1000 cc. of water. One cc. of this solution 
will be equivalent to one tenth of a milligramme of oxygen, as 
0.7875 mgm. of oxalic acid requires 0.1 mgm. of oxygen for con- 
version to carbonic acid. Dissolve 0.500 gm. of pure potassium 
permanganate in 1000 cc. of water, and dilute until 1 cc. of the 
solution exactly oxidizes I cc. of the oxalic-acid solution. Then 
I cc. of the potassium-permanganate solution carries one tenth 
of a milligramme of available oxygen. 

To .200 cc. of the water add 3 cc. of dilute sulphuric acid, 
and then froma burette the permanganate solution until the 
color produced by it ceases to disappear after allowing to stand 
three hours. From the number of cc. of permanganate solu- 
tion used calculate the quantity of oxygen required to oxidize 
organic matter. It is assumed that the oxygen required mul- 
tiplied by 8 is equivalent to organic matter. 

Free and Albuminoid Ammonia.—The determination of 
these requires the following solutions: 

Nessler’s Solution.—Dissolve 50 gms. of potassium iodide in 
a small quantity of hot water, place the solution on a boiling- 


water bath; cool, add, with frequent agitation, a strong solution — 


of mercuric chloride (40 gms. of the salt and 300 cc. of water), 
until the red precipitate just redissolves; filter; add to the 
filtrate a strong solution of potassium hydrate containing 200 
ems. of the salt; filter; dilute to 1000 cc., add 5 Cc, otvasauue 
rated solution of mercuric chloride, allow the precipitate formed 
to settle, decant the clear liquid, and keep for use in a tightly 
stoppered bottle. 

Sodium-carbonate Solution—Add 100 gms. of sodium car- 
bonate to 200 cc. of distilled water free from ammonia, and 
keep in a well-corked bottle. 

Potassium-permanganate Solution.—Dissolve 200 gms. of 
potassium hydrate and 8 gms. of potassium permanganate in 


oS 


ANALYSIS OF WATER. 279 


1000 cc. of distilled water free from ammonia, boil hard for 
half an hour in a two-litre flask to expel ammonia, and keep in 
a well-corked bottle. | 

Ammonium Solution.—Dissolve 0.3883 gm. of ammonium 
sulphate or 0.315 gm. of ammonium chloride in 1000 cc. of 
pure distilled water free from ammonia. One cc. of either 
solution will contain one tenth of a milligramme of ammonia 
(NHi.). For use dilute to ten volumes, so that each ce. will 
contain one hundredth of a milligramme of ammonia. 

DNistilled Water free from Ammonia.—To ordinary distilled 
water add a little sodium carbonate, and boil, in a large flask, 
until about one fourth is evaporated, then distil the remainder 
from a retort holding about 1500 cc. until the distillate gives 
no reaction for ammonia with Nessler’s solution, testing 50 cc. 
of the distillate at a time. When no more ammonia can be 
detected, distil off into a large flask 750 cc., and test again to 
be sure the 750 cc. are free from ammonia. Proceed in this 
manner until sufficient is prepared, and keep the water in 
tightly stoppered bottles. 

Free Ammonia.—To determine the free an. monia in a water 
connect a glass retort of at least 1000 cc. capacity with a 
condenser, and cleanse the apparatus by distilling some clean 
iwaeereninittoduce 200 cc. of clean, water and 15 cc. of the 
sodium-carbonate solution, and distil until the distillate is free 
from ammonia. Now introduce 500 cc. of the water to be 
tested, and distil, collecting the distillate in test cylinders. In 
other cylinders of the same calibre add amounts of the stand- 
ard ammonia solution containing, respectively, 0.01, 0.02, etc., 
mgm. NH,, and dilute.each up to 50 cc. with the especially 
prepared distilled water. When 50 cc. have distilled over, 
add 1.5 cc. of the Nessler solution to each cylinder. Care 
should be exercised to always use the same Nessler solution, 
the same amounts, and to allow it to act as nearly as possible 
for the same length of time. After allowing the cylinders to 
- stand a few minutes compare the tint of the distillate with those 
of the comparison cylinders, and thus estimate the amount of 
ammonia present. Test each succeeding 50 cc. in the same 


280 A MANUAL OF PRACTICAL ASSAYING. 


way, and proceed until the last 50 cc. tested contains less than 
o.or gm. of NH,. The whole amount of ammonia thus deter- 
mined is the total free ammonia. Should the water contain 
much ammonia it is safer to thoroughly mix each 50 cc. of the 
distillate and take out 10 cc., dilute it to 50 cc., and test as 
above. The remaining four fifths of the distillate may be used 
to confirm the results thus obtained. 

Albuminoid Ammonia.—After having determined the free 
ammonia as above, add 50 cc. of the permanganate solution to 
the contents of the retort and distil until the distillate no longer 
shows the presence of ammonia. Now add 500 cc. of the water 
to be tested, and distil, testing each 50 cc. of the distillate, as 
before, until it contains less than 0.01 mg.of NH,. This gives 
the total ammonia. The difference between the total and the 
free gives the albuminoid ammonia. 

Nitrates.—The following method is quite simple, and ap- | 
parently more accurate than the usual method.* Rinsea 100-cc. 
Nessler tube with the water to be tested, and then fill to the 
10o-cc. mark with the water to be tested. .Drop in 5 to 10 gms. 
of freshly-prepared sodium amalgam, the amount varying with 
that of the nitrates presumably present. Enough should be 
added to keep up the action at ordinary temperatures for at 
least two hours. Cover with a watch-glass, and allow the tube 
to stand in an atmosphere free from ammonia vapors, after 
adding one or two drops of concentrated hydrochloric acid (free 
from ammonium salt). After two hours the solution should 
only be faintly acid; if decidedly acid, add more sodium amal- 
gam, and continue the reduction. Finally, filter through a 
small filter previously freed from all traces of ammonia and 
Nesslerize 50 cc. of the filtrate in the usual manner. Deduct 
the free ammonia which the water contains, as determined in 
a separate portion, and calculate the results as usual. 





* School of Mines Quarterly, Vol. XV, No. 1, p. 11. 


ANALYSIS OF WATER. 281 


Grouping of the Constituents.—It is impossible to give 
any exact rule for the proper grouping of the constituents, as 
determined by the analysis. The following will answer for 
ordinary water: Combine the sodium with chlorine as sodium 
chloride. Should there be more sodium than the chlorine will 
satisfy, combine the excess with sulphuric acid as sodium sul- 
phate. Should there not be sufficient sulphuric acid to satisfy 
all the sodium, combine the excess with carbonic acid as 
sodium carbonate. Combine the potassium with sulphuric acid 
as potassium sulphate. Should there be more sulphuric acid . 
than the potassium and the excess of sodium (over NaCl) will 
satisfy, combine the excess first with calcium as calcium sul- 
phate, and any’ further excess with magnesium as magnesium 
sulphate. Should the water contain a large amount of chlorine 
(in excess of the amount sufficient to satisfy the sodium), and 
not sufficient sulphuric acid to satisfy the potassium, combine 
the excess of potassium with chlorine, and should there be any 
chlorine still left, combine it first with magnesium, and if there 
is still an excess, combine it with calcium. Calculate all cal- 
cium and magnesium not combined with chlorine and sulphuric 
acid to carbonates. 


CHAPTER XIII. 
ACIDIMETRY AND ALKALIMETRY. 


ACIDIMETRY and alkalimetry is the determination of the 
amount of acid or alkali which a solution contains. It is ac- 
complished by means of standard alkali and standard acid so- 
lutions and suitable indicators. 

Standard Acid Solutions.—The usual solutions employed 
are solutions of sulphuric, hydrochloric, and nitric acids in 
water. In addition to these, other acid solutions, as oxalic 
and acetic, are occasionally employed. The choice of the acid 
will depend largely upon the character of the substance to 
be analyzed, certain acids being particularly adapted to cer- 
tain determinations. 

Half-normal Sulphuric Acid.—This solution is prepared so 
that it will contain exactly 0.04 gm. of SO, or 0.049 gm. of 
H,SO,in each cc. To prepare the solution add 33.3 cc. of c. p. 
concentrated sulphuric acid to 1000 cc. of water, mix thor- 
oughly, and allow to cool to the normal temperature of the 
laboratory. Partially fill a burette with the solution, and draw 
off into beakers two separate portions of exactly 15 cc. each. 
To each portion add about 50 cc. of water and 30 cc. of a 
saturated solution of barium chloride, having both the acid 
solution and the barium-chloride solution at the boiling-point 
when the additionis made. Filter off the precipitates of barium 
sulphate, and determine the sulphuric acid as usual. If the 
precipitates do not differ in weight more than 0.01 gm., take 
the average and calculate the sulphuric acid in I cc. of the 
solution. Suppose the calculation shows that Icc. of the solu- 
tion contains 0.042 gm. of SO, in place of 0.04 gm., then it is 

282 


ACIDIMETRY AND ALKALIMETRY. 283 


too strong and requires dilution. As I cc. contains 0.042 gm., 


1000 cc. will contain 42 gms. in place of 40 gms., which it should 
contain; consequently, 


40 gms. : 1000 cc. 3: 42 gms. : 1050 cc. 


Hence 50 cc. of water must be added to each 1000 cc. of the 
acid solution to make it half normal. To do this fill a dry 
1000-cc. flask to the holding mark with the solution, pour the 
solution from the flask into a clean dry bottle, run into the 
flask 50 cc. of water, shake well, and pour off into the bottle. 
Shake the bottle well and pour back into the flask; finally pour 
back into the bottle, where it is kept for use. The sulphuric 
acid should be determined in the solution again, and the solu- 
tion corrected as before. 

Normal Nitric Actd.—To prepare this solution add 100 cc. 
Cieemmenitriceacid Of 1.32 sper. to 765 cc. of water and 
thoroughly mix. The best method of determining the 
strength of this solution is by means of a normal solution of 
potassium or sodium hydrate which has previously been 
accurately standardized. One cc. of the acid solution should 
exactly neutralize 1 cc. of the standard alkali solution. Have 
two burettes in a stand, and fill one with the acid solution to be 
tested and the other with the standard alkali solution. Draw 
off 10 cc. of the acid solution, dilute with 100 cc. of water, 
add a few drops of a suitable indicator, as litmus solution, and 
run in the standard alkali solution until the color just changes 
from red to blue. Take the reading of the burette and run in 
another 10 cc. of the acid solution, and titrate again with the 
standard “alkali solution. The two readings of the burette 
should agree closely Suppose this trial shows that 10 cc. of 
the acid solution neutralizes 12 cc. of the standard alkali solu- 
tion, then the acid solution is too strong and requires dilution. 
In this case every 100 cc. of the acid solution should be diluted 
to 120 cc. Measure off 800 cc. of the acid solution and add 


-160 cc. of water, thoroughly mix as in the case of the sul- 


phuric-acid solution, and restandardize, continuing the opera- 
tion until the acid solution exactly neutralizes the standard 


284 A MANUAL OF PRACTICAL ASSAYING. 


alkali solution, cc. for cc. The nitric-acid solution should con. 
tain 0.063 gm. of nitric acid in each cc. 

Normal Hydrochloric Actd@.—The normal hydrochloric acid 
solution should contain 0.0365 gm. of hydrochloric acid in 
each cc. To prepare this solution mix 1000 cc. of water with 
200 cc. of c. p. hydrochloric acid of 1.12 sp. gr. The amount of 
hydrochloric acid in each cc. of the thoroughly mixed solution 
may be determined in several ways. If some standard alkali 
solution is on hand, its standard may be readily determined by 
the same method as described above for nitric acid. If it is 
desired to determine the hydrochloric acid in each cc. directly, 
the following method is as good as any: Draw off two por- 
tions of the acid solution of exactly Io cc. each into a flask 
with sloping sides. Dilute with warm water, and precipitate the 
chlorine completely with a strong solution of nitrate of silver. 
Shake the flask, fill it completely with warm water, and invert 
it over a porcelain crucible of suitable size. Allow the precip- 
itate to settle completely into the crucible, remove the flask, 
and pour off the water from the crucible. Remove the last 
particles of water from the crucible with a piece of blotting- 
paper, being careful not to remove any of the precipitate. 
Evaporate off the last traces of water, and dry the crucible and 
its contents in a drying-chamber. When thoroughly dry, heat 
over a low flame until the silver chloride begins to fuse around 
the edges; cool, and weigh. Deduct from this weight the 
known weight of the crucible. The remainder will be the 
weight of the silver chloride. To obtain the weight of the 
chlorine multiply this weight by $42. From this weight calcu- 
late the number of cc. of water or hydrochloric acid to add to 
a given quantity of the acid solution in order to make it nor- 
mal. Make the necessary addition, and restandardize as before. 

Half-normal Oxalic Acid.—To prepare this solution dis- 
solve 63 gms. of c. p. crystallized oxalic acid in 1000 cc. of 
water, and standardize by titrating a portion with standard 
‘alkali solution ; or the oxalic acid may be determined by means 
of a standard solution of potassium permanganate. (See Part 
II, Chap. XVI, Iron.) 


ACIDIMETRY AND ALKALIMETRY. 285 


As the oxalic- and sulphuric-acid solutions are readily and 
accurately standardized, they are extremely useful in making 
up different standard acid and alkali solutions. Once having 
obtained a perfectly normal acid solution, the other solutions 
are readily obtained by standardizing with the normal or half- 
normal acid solution. 

Standard Alkali Solutions.—The solutions generally em- 
ployed are normal potassium-hydrate, normal sodium-hydrate, 
and occasionally half-normal sodium-carbonate solutions. 

Normal Potasstum Hydrate.—This solution should contain 
exactly 0.0561 gm. of potassium hydrate, or 0.0471 gm. of 
potassium oxide (K,O), in each cc. To prepare the solution 
dissolve 40 gms. of pure potassium hydrate in 600 cc. of water, 
and when dissolved mix thoroughly and fill a burette with 
the solution. Run into a beaker exactly Io cc. of the stand- 
ard sulphuric acid (or other standard acid) solution, dilute 
with water to about 200 cc., add a few drops of the indicator, 
and run in the potassium hydrate solution, drop by drop 
towards the last, until the color changes. Note the reading of 
the burette, and add another 1occ. of the acid solution and 
titrate again. Repeat this titration several times, and take 
the average of the different determinations, provided they 
do not differ too much. The color imparted to any number 
of cc. of the acid solution by the indicator should change upon 
the addition of the same number of cc. of the alkali solution. 
If it does not, the potasstum-hydrate solution should be diluted 
or strengthened until the two agree. Suppose it only re- 
quired 9 cc. of the potassium-hydrate solution to neutralize 
10 cc. of the half-normal sulphuric acid solution. Then every 
9 cc. of the alkali solution requires I cc. of water, or 500 cc. 
of the alkali solution require 55.5 cc. of water. 

Normal Sodium Hydrate.—Every cc. of this solution should 
contain exactly 0.04 gm. of sodium hydrate or 0.031 gm. of 
sodium oxide (Na,O). To prepare this solution dissolve 28 
ems. of pure sodium hydrate in 600 cc. of water, mix, and 
titrate as in the case of the potassium-hydrate solution. 

Indicators.—This is the name given to the coloring mat- 


286 A MANUAL OF PRACTICAL ASSA YING. 


ters used to show when the fluid is acid or alkaline. <A great 
number have been proposed, of which the following are most 
commonly used : 

Litmus.—A solution of litmus is prepared by boiling the 
coarsely powdered litmus with alcohol of about 80 per cent 
two or three times, and discarding the liquid so obtained. The 
litmus is now digested repeatedly with cold water until all the 
soluble coloring matter is extracted. Allow the mixed wash- 
ings to settle, decant the clear liquid, and add a few drops of 
concentrated sulphuric acid until the solution is quite red. 
Heat to boiling to decompose the alkaline carbonates and con- 
vert them into sulphates, and then gradually add baryta-water 
until the blue color is restored. Allow the precipitated barium 
sulphate to settle completely, and decant the solution into an 
open bottle.. The solution must be kept in an open bottle, and 
in a place free from acid or alkaline fumes. It cannot be used 
in the presence of carbonic acid. 

Cochineal.—Take about 3 gms. of powdered cochineal and 
macerate, frequently shaking, with a mixture of distilled water 
and alcohol (3 volumes of water and 1 volume of alcohol). 
Filter into a stoppered bottle. It should be kept tightly 
corked. It cannot be used in the presence of iron salts, but 
is not affected by carbonic acid in moderate quantities. The 
solution is yellow when acid, and carmine when alkaline. 

Coralline-——Dissolve some coralline in alcohol and filter 
if necessary. Keep ina closed bottle. The solution becomes 
straw color when acid. It is particularly well adapted to the 
titration of acetic and other organic acids. 

Methyl Orange-—This is a very sensitive indicator for 
mineral acids. 

Phenolphthalein.—This is a very sensitive indicator, and is 
used in the titration of solutions of molybdic acid. 

Logwood.—It must be kept unexposed to the light, and can- 
not be used in the presence of the oxides of the heavy metals. 
To prepare, boil a few shavings of the logwood with distilled 
water and mix the concentrated solution with 1 or 2 volumes 
of alcohol. 


ACIDIMETRY AND ALKALIMETRY. 287 


These standard solutions have a great number of uses in 
analytical chemistry. A few of their applications will serve to 
show the manner of using them. 

Determination of Potassium Hydrate in Commercial Caustic 
Fotash.—\n order to save time and possible errors in the calcu- 
lation of results it is best to weigh out an equivalent part. As 
the molecular weight of caustic potash is 56.1, a one-tenth 
equivalent would be 5.61 gms. Weigh out this amount, dis- 
solve in a little hot water, filter, and thoroughly wash the 
residue, filtering into a 10o-cc. flask. Bring the bulk of the 
solution up to exactly 100 cc., and thoroughly mix by pouring 
from the flask into a dry clean beaker and from the beaker | 
back into the flask, repeating several times. Filla burette with 
the solution and draw off exactly Ilo c.c. into a beaker. Run 
in 10 cc. of the half-normal sulphuric acid, dilute to about 50 
cc. with water, and add a few drops of the indicator. Now 
run in normal potassic-hydrate solution until the solution is 
exactly neutral. Repeat on several other portions of Io cc. 
each, and take the average. If the caustic potash contained 
100 per cent of KOH, the tocc. of acid would have just neu- 
tralized the 10 cc. of alkali solution taken. Suppose 2 cc. of 
the normal potassic-hydrate solution were used: then without 
calculation we see at once that the commercial alkali contains 
80 per cent potassium hydrate. 

Analysis of Commercial Acetic Actd.—Weigh out, in a 
counterpoised beaker, 30 gms. of the acid, wash with water 
into a 500-cc. flask, and dilute with water to the holding mark. 
Draw off with a pipette 100 cc., run into a beaker, and adda 
few drops of a suitable indicator. Coralline is preferable in thig 
case. Nowrunin normal potassium-hydrate solution until a 
full alkaline color is obtained. The color should be full alka- 
line, as neutral alkaline acetates have a slight alkaline reaction. 
Note the reading of the burette and calculate the per cent of 
acid. If 30 gms. of acid were taken and diluted to 50o-cc., of 
which solution 100 cc. were taken for titration, each cc, of 
normal alkali solution will represent I per cent of acid. 

If it is desired to know the weight of acid in so many gal- 


288 A MANUAL OF PRACTICAL ASSAYING. 


lons of acid, weighing of the solution is unnecessary. In this 


case measure out a portion of acid, dilute, and take an aliquot | 


portion for titration. 

As commercial acetic acid frequently contains both sul- 
phuric and hydrochloric acids, simple titration will not show 
the percentage of acetic acid in the case of an impure acid. 
In this case the hydrochloric acid may be determined volu- 
metrically by means of a standard solution of silver nitrate, 
using potassium chromate as anindicator. The suphuric acid 
should be determined by acidifying a weighed portion of the 
acetic acid with hydrochloric acid, diluting with water, boiling, 
and precipitation with barium-chloride solution. The weights 
of hydrochloric acid and sulphuric acid so found are then cal- 
culated to their proper equivalents in cc. of normal potassium- 
hydrate solution, and the corresponding deduction from the 
total number of cc. of potassium hydrate used is made. The 
difference will show the per cent of acetic acid present. For 
example, suppose 3 gms. of acetic acid were taken and the 
hydrochloric acid found was 0.031 gm. For the determination 
of sulphuric acid 3 gms. were also taken, the result being .025 
gm. sulphuric acid. Nowas 6 gms. of acetic acid are taken 
for titration in each case, we have in the 6 gms. 0.062 gm. of 
hydrochloric and 0.05 gm. of sulphuric acid. The hydrochloric 
acid would neutralize 1.7 cc. of the normal alkali solution and 
the sulphuric acid would neutralize 1 cc. of the normal alkali 
solution; hence from the total number of cc. of the normal 
alkali solution used in the titration a deduction of 2.7 cc. 
should be made for the hydrochloric and sulphuric acids 
present. 


vi Ares 


GEE TE Ke XN, 
CHLORIMETRY. 


CHLORIMETRY has for its object the determination of the 
available chlorine of bleaching-powder. 

Bleaching-powder, which is commercially known as chloride 
of lime, consists of a mixture, or combination, of calcium hypo- 
chlorite (CaCl,O,) and calcium chloride (CaCl,). Its value for 
commercial and metallurgical purposes will depend upon the 
amount of chlorine set free (available chlorine) when an acid 
is added. The reaction which takes place is as follows: 


Ca(Cl10), , CaCl, + 2H,SO, = 2CaSO, + 2H,O + 4Cl. 


Hence the available chlorine is two atoms of Cl for each atom 
of O in the hypochlorite. 

A number of methods have been proposed for the estima- 
tion of the chlorine set free. The following is believed to be 
as simple and accurate as any: 

Weigh out 10 gms. of the bleaching-powder, transfer to a 
porcelain mortar, add about 50 cc.’of water, and rub into a 
cream. Allow the coarse particles to settle, pour off the turbid 
fluid into a 1000-cc. flask, add more water, rub again, and pour 
off into the flask, continuing the operation until all of the 
powder is transferred to the flask. Fill the flask with water 
to the holding mark, pour the solution into a dry beaker, mix 
thoroughly, and draw off 50 cc. for analysis with a pipette. 

Weigh out 0.325 gm. of piano-forte wire, dissolve it ina 
valve flask with about 1occ. of dilute sulphuric acid (1 part 


H,SO and 5 parts H,O), cool, fill the flask with water, and. 
289 


290 A MANUAL OF PRACTICAL ASSA VYING. 


pour into a beaker. To the solution in the beaker add the 
50 cc. of turbid bleaching-powder solution, allowing it to run 
in slowly from the pipette and stirring constantly. Dilute to — 
about 500 cc., and determine the iron remaining in the ferrous 
form by means of a standard solution of potassium permanga- 
nate. The same solution of permanganate as is used for the 
determination of iron (see Part II, Chapter XVI) is used for 
this purpose. Four atoms of iron correspond to four atoms 
of chlorine, or 56 parts of iron are equivalent to 35.5 parts of 
chlorine, as is shown by the reaction : 


4¥e50,-- Ca(ClO), , CaGi ia 
2Fe(SO,), + 2CaCl, + 2H,O. 


The method of calculating the result is best illustrated by 
the following example: Suppose I cc. of the permanganate 
solution equals 0.005 gm. of iron, and that 16 cc. of the solu- 
tion were used in the determination. Hence (.005 K 16 = .08) 
0.08 gm. of the 0.324 gm. of the iron taken remained unoxid- 
ized by the bleaching-powder used. Then 0.324 — 0.08 = 
0.244 gm. of iron which was oxidized by the bleaching-powder. 
Hence 


56 : 35.5 :: 0.244: 0.1547 gm. available Cl. 


Consequently, as 0.5 gm. of bleaching-powder was taken for 
analysis, the per cent of available chlorine = 30.94. 

Another method consists in running 50 cc. of the turbid 
bleaching powder sulution into a flask and adding an excess of 
potassium iodide solution. The whole of the available chlorine 
displaces an equivalent quantity of iodine; thus, 


Ca (C1O),, CaC1, + 4K1 = 414 4K Glee 


which may be determined by titration with a standard solution 
of sodium hyposulphite. (See pages 97 and 161.) 


ae ee 
oe . 


Grrr Re XV, 
ANALYSIS OF WHITE-LEAD. 


THE white-lead of commerce, when pure, is a basic carbon. 
ate ot lead (2PbCO,, PbO,H,). Its value, from a chemical 
standpoint, depends upon the percentages of PbO, CO,; and 
H,O which it contains, and these percentages should corre- 
spond pretty closely with the theoretical percentages of the 
formula. 

In a white-lead works manufacturing a pure quality of 
white-lead all that is generally required is the percentages of 
Poe. cand’ H.O: | 

The white-lead of commerce is frequently adulterated, the 
principal adulterants used being zinc-white (ZnO) and heavy 
spar (BaSO,). Some white-leads contain lead sulphate (PbSO,). 

The best method of determining the water and carbonic 
acid is by direct weight. The determinations are effected as 
follows: Weigh out from I.0 to 2.0 grammes of the white- 
lead in a porcelain boat, and introduce it into a piece of com- 
bustion-tubing. To the right-hand end of the tube a chloride- 
of-calcium tube, which has been previously filled with fresh, 
dry calcium chloride, and weighed, is attached. The calcium- 
chloride tube is attached to a U-tube filled with freshly ignited 
soda-lime. The U-tube is weighed before connecting up the 
apparatus. The U-tube is attached to another U-tube filled 
with pumice saturated with sulphuric acid. (See determina- 
fiom of carbonic acid, Part II, Chap. V.) The last U-tube is 
connected with an aspirator. The left-hand end of the com- 
bustion-tube is connected with a U-tube containing pumice 
and sulphuric acid and a U-tube containing soda-lime, in order 

291 


292 A MANUAL OF PRACTICAL ASSA YING, 


that the air passing through the apparatus shall be dry and free 
from carbonic acid. After connecting up the apparatus the 
aspirator is started, and after it has ran a few minutes the boat 
containing the white-lead is gradually heated by the flame of a 
Bunsen burner. The heat is gradually increased. After 10 to 
15 minutes’ heating all the water and carbonic acid should be 
driven off from the lead. The burner is now removed, and 
the aspirator kept running until the absorption-tubes have 
cooled. The soda-lime and calcium-chloride tubes are now 
disconnected and weighed, the increase in weight of the cal- 
cium-chloride tube representing the water which the white- 
lead contained, and the increase in weight of the soda-lime 
tube representing the carbonic acid which the white-lead con- 
tained. Should the lead be pure, the difference between the 
sum of the percentages of carbonic acid and water and 100 
will be the percent of lead oxide (PbO). As commercial white- 
lead usually contains some lead acetate, the residue, after treat- 
ment as above to drive off water and carbonic acid, is weighed. 
In pure white-lead this weight may be taken as lead oxide. 

In the case of an impure lead, treat I.0 to 2.0 grammes of 
the lead with 15 to 30 cc. of pure, strong acetic acid. Warm 
to effect solution, and when the white-lead is thoroughly de- 
composed, filter through a small filter and wash thoroughly 
with warm water.. The filtrate will contain all the lead which 
was combined as carbonate. This may be determined accord. 
ing to Part II, Chapter IX. 

Treat the residue with a strong, hot solution of ammonium 
chloride, and filter. The filtrate will contain the lead com- 
bined as sulphate. This may be determined according to 
arte lL wCGhapters ln. 

The residue will contain the barium sulphate, etc., which 
may be determined according to Part II, Chapters I and 
XXV. 

To determine the zinc oxide, dissolve 1.0 to 2.0 grammes 
of the white-lead in dilute hydrochloric acid and determine 
volumetrically with a standard solution of potassium ferro- 
cyanide, (Sée Part 11) Chapter: <0 1s) 





CHAPTERS XVI: 
SPECIFIC-GRAVITY DETERMINATIONS. 


THE specific gravity of any body is the weight of that 
body as compared with the weight of an equal volume of 
another body which is assumed asa standard. The standard 
taken for solids and liquids is distilled water; for gases and 
vapors, dry air and occasionally hydrogen. 

All determinations of solids and liquids: must be made at 
the same temperature. The temperature usually adopted is 
60° Fahrenheit. 

Determinations of gases and vapors may be made at any 
known temperature, and the volumes reduced to what they 
would be at 60° Fahrenheit. 

Solids.—1. The substance is heavier than water and insol- 
-uble in water. 

Weigh first in the air, suspending the substance from the 
beam of the balance by a piece of horse-hair, and then in dis- 
tilled water whose temperature is 60° F. Let W= the weight 
in air, W’= the weight in water, and Sp. gr.= the specific grav- 
ity ; then 


Vie 
Sp. gr. — Wea Wwe 
2. The substance is heavier than water and insoluble in 


water, but is in fragments. 
Fill a specific-gravity bottle* with distilled water whose 





*If a specific-gravity bottle is not at hand, take a thin-glass flask witha 
narrow neck and scratch a mark on the neck. The flask is to be filled to this 
mark in the determinations. 

293 


204 A MANUAL OF PRACTICAL ASSA YING. 


temperature is 60° F., and weigh it. This weight = W’. Weigh 
the substance in the air. This weight = W. Now introduce 
the weighed substance into the flask, fill it with distilled water, 
and weigh. This weight = W”: 


oo I Pa 
Pp- gr. es (W+ W’) =. Ww” 


3. The substance is heavier than water, but soluble in it. 

Weigh the substance in the air. This weight => W. Now 
weigh it in some liquid in which it is insoluble and whose 
specific gravity is known. This weight = W’. Hence we 
have the proportion, the specific gravity of water being 1, 


Sp. gr. of liquid: 1=(W— W’): W", 


in which W” = the weight of water which would have been 
displaced. 


W 
Spach Wr 


4. The substance is lighter than water and insoluble in it. 

Weigh the substance in air. This weight =W. Weigh a 
piece of lead of suitable size in water. This weight =W’". 
Weigh the substance and the piece of lead together in water. 
This weight =W”, 


S Pepe 
Pp. gr. = W— (We + Ww’) 


5. The substance is lighter than water and soluble in it. 

Weigh the substancein the air. This weight = W. Intro- 
duce the substance into the flask described in 2, and fill the 
flask with some liquid in which it is insoluble, and whose 
specific gravity is known. Weigh. This weight = W’. Fill 
the flask with the liquid alone and weigh. This weight = 
W”’. Then the weight of the liquid displaced = W” — ’ = 
A. If S =the specific gravity of the liquid, and_Y = the corre 





F 





SPECIFIC-GRAVITY DETERMINATIONS. 295 


sponding weight of water which would have been displaced, we 
have 


W 
: I Sas A i? XY d e e — aaceraaal | 
> 5 EMG lah yeh tage ¥ 


Liquids.—One of three methods may be employed. 
6. Weigh some body, which is insoluble in water and in the 


fiquid, first in air, then in water, and then in the liquid. 


Let W =the weight in air; 
'W’ =the weight in water; and . 
W” = the weight in the liquid. Then 


Cette Ge 
P Sl. = Tap 


7, The specific-gravity bottle is employed, which for liquids 
is usually provided with a hollow-glass stopper which allows 
the insertion of a thermometer. 

Let W =the weight of the flask empty; 

W’ = the weight of the flask filled with water; 
W” = the weight of the flask filled with the liquid. 


S = Aad dG ene 
esas Opry ae wv 


8. By means of a hydrometer. 

The principle upon which the hydrometer depends is that 
a floating body displaces its own weight of liquid. 

Special hydrometers are made, the graduations being for 
liquids of different specific gravities, as the lactometer for milk 
and the uriometer for urine. 

The Baumé scale of graduation is frequently used in com- 
mercial work. It is purely arbitrary. For liquids heavier than 
water the point to which the hydrometer sinks in a 15-per-cent 


solution of sodium chloride in water (NaCl 15 parts, H,O 85 


parts) is marked 15°. The point to which it sinks in pure 
water is marked 0°. For liquids lighter than water the point 
to which the hydrometer sinks in pure water is marked 10°, 


266 A MANUAL OF PRACTICAL ASSA YING. 


The point to which it sinks in a 10-per-cent sodium-chloride 
solution (NaCl 10 parts, H,O go parts) is marked 0°. 

The observations of Baumé were conducted at 10° R. = 
54.5° F. 

For liquids heavier than water the degrees Baumé can be 
converted into specific gravity by the formula 
144 
Sp. gr. = ———*.. 

Deas ane 

For liquids lighter than water the degrees Baumé can be 

converted into specific gravity by the formula 


ht 
Sp. gr. = ————... 
oa 134 +B 
For specific gravities corresponding to degrees Baumé, see 


page 207. . 

Gases.—The specific gravity of a gas or vapor may be 
determined by Bunsen’s method, which consists in weighing a 
glass globe when filled with air, when filled with the gas, and 
when exhausted by means of an air-pump. From the data so 
obtained the specific gravity can be readily calculated. As 
this method requires a powerful air-pump it is seldom used 
except for scientific work. (See Watts’ Dictionary of Chem- 
istry.) 

For commercial work the Schilling effusion method is com- 
monly used. In this method the times of the effusion of equal 
volumes of gas and air through a fine hole in a thin metallic 
plate are compared. It depends upon the principle that the 
specific gravities of two gases passing through such an opening 
are proportionate to the squares of the times of effusion. 

Let A = seconds which the volume of air requires to escape ; 

B = seconds which the same volume of gas requires to 
escape ; 
x = the specific gravity of the gas. 
If the specific gravity of air = I, we have 
BB? 


lait At ators 


eee ee eS es 


SPECIFIC-GRAVITY DETERMINATIONS. 297 


SPECIFIC GRAVITIES OF LIQUIDS HEAVIER THAN WATER.* 
TEMPERATURE 54.5° F. 











fare Specific Gravity. (eee Specific Gravity. Pe a Specific Gravity. 
fe) 1.00000 26 1.21129 52 1.53580 
I 1.00675 27 1.22122 53 1.55179 
“2 1.01360 28 1.23131 54 1.56812 
3 1.02054 29 1.24156 55 1.58479 
4 1.02757 30 1.25199 56 1.60182 
5 1.03471 31 1.26260 57 1.61923 
6 1.04194 32 1.27338 58 1.63701 
7 1.04927 33 1.28436 59 1.65519 
8 1.05671 34 1.29552 60 1.67378 
9 1.06426 35 1.30688 61 1.69279 
10 1,07IQI 36 1.31844 62 1.71223 
II 1.07968 37 1.33021 63 1.73213 
12 1.08755 38 1.34218 64 1.75250 
13 1.09555 39 1.35438 65 1.77335 
14 1.10366 40 1.36680 66 1.79470 
15 I. 11189 41 1.37945 67 1.81657 
16 1.12025 42 1.39234 68 1.83899 
17 1.12873 43 1.40547 69 1.86196 
18 1.13735 44 1.41885 70 1.88551 
19 1.14609 45 1.43248 71 1.90967 
20 1.15497 46 1.44638 Gi 1.93446 
21 1.16399 47 1.46056 73 1.95989 
22 1.17316 48 1.47501 74 1.98601 
23 1.18246 49 1.48975 75 2.01283 
24 I.IgIg2 50 1.50479 
25 1.20153 51 1.52014 





SPECIFIC GRAVITIES OF LIQUIDS LIGHTER THAN WATER.+ 
TEMPERATURE 54.5° F. 














Re cce Specific Gravity. pees ee Specific Gravity. aabee Specific Gravity. 
10 1.00000 35 0.85342 60 0.74432 
15 0.96679 4o 0.82912 65 0.72577 
20 0.93571 45 0.80616 70 0.70811 
25 0.90657 50 0.78443 75 0.69130 
30 0.87919 55 0.76385 


* “ The Baumé Hydrometer,” a paper read by Prof. C. F. Chandler before 
the National Academy of Sciences, at the Philadelphia meeting, 1881. 
t Ibid. 


CHAPTER XVII. 
ANALYSIS OF COMMERCIAL ALUMINIUM. 


THE constituents usually required are silicon, iron, copper, 
and aluminium. The method of decomposition described is 
due to Rossel.* 

Three grammes of the finely-divided metal are gradually in- 
troduced into from 30 to 40 cc. of hot caustic potash (30 to 40 
per cent solution). The potash should be pure, and free from 
silica, alumina, etc. The decomposition is best effected ina 
platinum dish, as the caustic potash attacks glass or porcelain. 
The metal dissolves, leaving a black flocculent residue. After 
the decomposition is complete the solution is supersaturated 
with pure hydrochloric acid and evaporated to dryness. The 
dusty dry mass is heated at 110° C. to dehydrate the silicic 
acid, moistened with hydrochloric acid, dissolved in water, and 
the silica filtered off, washed with hot water,.and determined 
as usual. From the silica, as found, calculate the percentage 
of silicon. 

To the filtrate from the silica add an excess of sulphuric 
acid, evaporate to drive off the hydrochloric acid, and finally 
dilute with cold water to 300 cc. Divide into two portions of 
100 cc. and 200 cc. each. 

In the 100 cc. portion (corresponding to I gm. of the origi- 
nal material) determine the aluminium by nearly neutralizing 





* Chem. Ztg. XXI. 4. 
298 


ee pa i? ~ 


poe, es 
, ye 


ANALYSIS OF COMMERCIAL ALUMINIUM. 299. 


the solution with ammonia, precipitating the iron by electroly- 
sis, and finally determining the aluminium as a phosphate in 
the manner described in Part II, Chapter XVII. 

In the 200-cc. portion (corresponding to 2 gms. of the orig- 
inal material) determine the iron by reduction with pure zinc 
and titration with a standard solution of potassium perman 
ganate, in the manner described in Part II, Chapter XVI. 

For the determination of copper dissolve 1.0 gm. of the 
metal in 40 cc. of a mixture of hydrochloric acid and water 
(HCl 33 per cent, H,O 67 per cent). When solution is effected, 
boil, dilute with hot water to 250 cc., and pass sulphuretted 
hydrogen through the solution until it is saturated. The cop- 
per sulphide and silicon are filtered off and washed, when the 
copper may be separated from the silicon and determined elec- 
trolytically (see page 157), or by any of the usual methods 
(Part II, Chap. XIII). 

For the analysis of titanium and chromium-aluminium 
alloys, and for much valuable information in regard to the 
analysis of commercial aluminium, see an article by Hunt, 
Clapp, and Handy. * 


* Jour. of An. and App. Chem., Vol. VI, No. 1, Jan. 1892. 


CHAPTER XVIII. 
ANALYSIS OF NATURAL PHOSPHATES. 


THE value of phosphate rock principally depends upon the 
percentage of phosphoric acid which it contains. In addition 
to the phosphoric acid the following substances affect the value 
of the material in the manner described: Water and insoluble 
matter, which reduce the percentage of phosphoric acid; car- 
bonates, which increase the cost of manufacture by neutralizing 
their equivalent of sulphuric acid; alumina and ferric oxide, 
which revert a portion of the soluble phosphoric acid and also 
have a tendency to render the superphosphates wet and un- 
manageable; and fluorine, which, as there are silicates of alu- 
minium otherwise undecomposed by sulphuric acid, which are 
decomposed in the presence of fluorine, the otherwise inactive 
alumina assuming an objectionable form. 

The following method of analysis is taken from an article 
by Dr. T. M. Chatard,* and whilst it differs somewhat from the 
methods of other chemists, it is believed to be as rapid and 
accurate as any method which we have. 

Moisture.—Two grammes are weighed into a tared plati- 
num crucible. This, with its lid, is placed in an air-bath at 
105° C., and heated for at least three hours. The lid is then 
put on, and the crucible is placed in a desiccator and weighed 
as soon as cold. The loss is the weight in moisture. 


* Transactions of The American Institute of Mining Engineers, Vol. XXI, 
page 160. 
300 


gi eee 
ie 


ANALYSIS OF NATURAL PHOSPHATES. 301 


Combined Water and Organic Matter.—The residue 
from the moisture determination is gradually heated to full red- 
ness over a lamp, and then ignited over the blast-lamp. This 
operation is repeated to constant weight. ‘The loss (less the 
percentage of carbonic acid as determined in another portion) 
may be taken as water and organic matter. This method an- 
swers for all technical purposes, but when minerals containing 
fluorine are strongly ignited, a part of the fluorine is expelled; 
hence, if more accurate determinations are required, the meth- 
ods given in Fresenius, etc., should be followed. 

Carbonic Acid.—The method by direct weight, using the 
apparatus described in Part II, Chapter V, may be followed. 
Many phosphates must be heated with dilute acids to the boil- 
ing-point to effect complete decomposition of the carbonates. 

Insoluble Matter.—Five grammes of the phosphate are 
placed in a beaker or casserole ; 25 cc. of nitric acid (sp. gr. 
1.2) and 12.5 cc. of hydrochloric acid (sp. gr. 1.12) are added; 
and the vessel, covered with a watch-glass, is placed on the 
water-bath for thirty minutes. The solution is stirred from 
time to time, and at the end of the thirty minutes the vessel 
is removed from the bath, filled with cold water, well stirred, 
and its contents allowed to settle. The solution is now filtered 
into a 500-cc. flask, and the residue is thoroughly washed with 
cold water, partially dried, and finally ignited to constant 
weight. This weight may be considered as insoluble matter. 
It will not correctly represent the silica, as the fluorine liberated 
during solution of the phosphate dissolves a portion of the 
silica. As the same reaction occurs in the manufacture of a 
superphosphate from the material, the result may be considered 
as a fair approximation to commercial practice. The ignited 
residue should be tested for P,O,. 

The flask containing the filtrate is filled up to the mark 
with cold water, and the solution is thoroughly mixed by 
pouring twice into a dry beaker and returning to the flask. 

Phosphoric Acid.—Two portions of 50 cc. each (=0.5 
em. of original material) are drawn off with a pipette, intro- 
duced into beakers, and evaporated until the hydrochloric acid 


302 A MANUAL OF PRACTICAL ASSA YING. 


is driven off. To each portion 150 cc. of molybdate solution ts 
added, the solution being well stirred and allowed to stand on 
a water-bath until quite hot. The beakers are now removed 
and allowed to stand until the solution is quite cold. It is 
best to allow the solutions to stand for at least three hours, 
after which the yellow precipitate is filtered off and well 
washed with a 20-per-cent solution of ammonium nitrate con- 
taining one-thirtieth of its volume of nitric acid. The filtrate 
should be tested for P,O, by the addition of some molybdate 
solution and digestion for some time. The funnel, with its 
contents, is now inclined over the beaker in which the precipi- 
tation was effected, and the precipitate washed back into it 
with a jet of water. Ammonia is now added, and on gently 
warming complete solution of the precipitate should be ef- 
fected. Any residue indicates either incomplete washing or, 
under some circumstances, silica. The solution is filtered 
through the same filter into a clean beaker, and the first beaker 
and the filter are thoroughly washed with dilute ammonia 
water (I part ammonia and 4 parts water). The solution is 
now boiled, the beaker is removed from the heat, and magne- 
sia solution is added: drop by drop, with continual stirring. 
The precipitate at first redissolves, but during the continual 
addition of the magnesia solution the solution becomes cloudy, 
with a flocculent precipitate, which, as the stirring continues, 
becomes crystalline and subsides. When further addition of 
the magnesia solution causes no cloudiness and the crystalline 
change ts complete, the beaker is placed in very cold water to 
chill its contents as rapidly as possible. When perfectly cold 
it is again tested with a few drops of, the magnesia solution, 
and if the precipitation is found to be complete, about one 
third of its volume of strong ammonia is added, the solution is 
stirred and allowed to stand three hours. The precipitate is 
finally filtered on an asbestos felt in a Gooch* perforated cru- 
cible, and washed with the dilute ammonia water. The wash- 
ing will be completed by the time the precipitate is completely 


* American Chemical Journal, Vol. I, p. 317. 


ANALYSIS OF NATURAL PHOSPHATES. 303 


removed from the sides of the beaker and transferred to the 
filter. A few drops of a strong solution of ammonium nitrate 
are poured on the precipitate, which is then carefully dried 
and gently heated until the fumes of ammonium salts cease to 
come off. The heat is now increased, and as soon as the glow 
of the pyrophosphate formation has passed through the whole 
of the precipitate the crucible is placed in a desiccator and, 
when cold, weighed. The ignited precipitate is very white, 
and the difference between the two determinations should not 
exceed 0.05 per cent for thoroughly satisfactory work. 

Should a Gooch crucible not be at hand, the ammonium, 
magnesium phosphate can be filtered onto a filter-paper, and, 
after washing, dissolved in dilute nitric acid into a small plati- 
num dish, the solution being evaporated to dryness, carefully 
ignited, and weighed. A clean mass is thus obtained, whilst, 
should the precipitate be ignited with the paper, it is difficult 
to destroy the carbon. 

Lime.—Evaporate 100 cc. of the solution (containing I gm. 
of the original substance) in a beaker to about 50 cc., add 10 
cc. of sulphuric acid (1 cc. sulphuric acid and 4 cc. water), and 
evaporate on a water-bath until a considerable crop of gypsum 
crystals are formed. Cool the solution, when it will generally 
become pasty owing to the additional separation of gypsum. 
When cold, 150 cc. of 95-per-cent alcohol are slowly added, 
with continual stirring, and the whole is allowed to stand for 
three hours, with occasional stirring. The precipitate is fil- 
tered off, with the aid of a filter-pump, into a distillation-flask, 
and washed with g5-per-cent alcohol. The filter, with the 
precipitate, is gently removed from the funnel and inverted 
into a platinum crucible, so that by squeezing the point of the 
filter the precipitate falls down into the crucible and the paper 
is pressed down smoothly over it. The crucible is gently 
heated, and when the alcohol has burned off and the paper is. 
completely destroyed the heat is raised to the full power of the 
Bunsen burner for a few minutes, after which the crucible is 
cooled and weighed. From the weight of the CaSO,, as thus. 
determined, the weight of the CaO is calculated. Separate 


304 A MANUAL OF PRACTICAL ASSAYING. 


determinations on the same sample rarely differ more than 0.05 
per cent. 

Ferric Oxide and Alumina.—The distillation-flask contain. 
ing the alcoholic filtrate is connected with a condenser and 
heated until alcohol is no longer distilled over. ‘This distillate, 
if mixed with a little sodium carbonate and redistilled over 
quicklime, can be used over and over again. When the dis- 
tillation is ended, the residue in the flask is washed into a 
small platinum dish and evaporated as far as possible on the 
water-bath. It becomes dark brown, owing to the presence of 
organic matter, which must be destroyed, since it prevents the 
complete precipitation of the phosphorus in the subsequent 
operation. To destroy this organic matter, remove the dish 
from the bath, add a small amount of pure sodium nitrate, and 
heat carefully over the naked flame, keeping the dish covered 
with a watch-glass. If care be taken, there will be no loss by 
spattering ; and the mass fuses to a colorless, viscous liquid, 
cooling to a glass, which is readily soluble in hot water made 
acid with nitric acid. The solution is transferred to a beaker, 
made slightly (but distinctly) alkaline with ammonia, then 
carefully neutralized with acetic acid, then diluted with hot 
water, brought toa boil, allowed to settle, and filtered. After 
the precipitate has been completely brought on the filter with 
hot water, the washing is completed with a solution of ammo- 
nium nitrate (made by neutralizing 5 cc. of nitric acid with 
ammonia and diluting to 250 cc.), and the precipitate is dried, 
ignited intensely, and weighed. As the determinations are 
made in pairs, one portion is used for the estimation of phos- 
phoric acid by fusing with a little sodium carbonate, dissolving 
in dilute nitric acid, and treating with molybdate solution as 
already described; while the other portion, also fused with 
sodium carbonate, is dissolved with sulphuric acid, and the iron 
is reduced and titrated with permanganate. The results should 
not differ more than 0.1 per cent. <6 

Magnesia.—The filtrate from the aluminium ferric phos- 
phate is evaporated to a small bulk, made strongly ammo- 
niacal, and allowed to stand, when magnesia, if present, will 


ee 1 tet a a 
ie 


MVNALYSIS OF NATCORAL PHOSPHATES, 305 


separate as the double salt, and should be treated as usual. If 
during the evaporation of the filtrate (which should be per- 
fectly clear at first) any flocculent matter separates, it should 
be filtered off and examined before proceeding with the pre- 
cipitation of the magnesia. 

Fluorine.—Two grammes of the phosphate are intimately 
mixed in a large platinum crucible with 3 gms. of precipitated 
silica and 12 gms. of pure sodium carbonate, and the mixture 
is gradually brought to clear fusion over the blast-lamp. 
When the fusion is complete, the mass is spread over the walls 
of the crucible, which is then cooled rapidly. The mass is 
detached from the crucible and put ina platinum dish, into 
which whatever remains adhering to the crucible or its lid is 
also washed with hot water. The contents of the dish are now 
diluted with hot water, the dish is covered and digested on the 
water-bath until the mass is thoroughly disintegrated. To 
hasten this the supernatant liquid may be poured off, the resi- 
due being washed into a small porcelain mortar, ground up, 
returned to the dish, and boiled with fresh water until no hard 
grains are left. The total liquid is then filtered, and the resi- 
due is washed with hot water. The filtrate (which should 
amount to about 500 cc.) is nearly neutralized with nitric acid 
(methyl orange being used as an indicator), some pure sodium 
bicarbonate is at once added, and the solution (in a platinum 
dish, if one large enough is at hand, otherwise in a beaker) is 
placed on the water-bath, when it speedily turns turbid through 
the separation of silica. As soon as the solution is warm it is 
removed from the bath, stirred, allowed to stand for two or 
three hours, and then filtered by means of the filter-pump and 
washed with cold water. The filtrate is concentrated to about 
250 cc. and nearly neutralized, as before; some sodium car- 
bonate is added; and the phosphoric acid is precipitated with 
silver nitrate in excess. The precipitate is filtered off and 
washed with hot water, and. the excess of silver in the filtrate 
is removed with sodium chloride. The filtrate from the silver 
chloride (after addition of some sodium bicarbonate) is evap- 
orated to its crystallizing point, then cooled and diluted with 


306 A MANUAL OF PRACTICAL ASSA YING. 


cold water; still more sodium bicarbonate is added, and the 
whole is allowed to stand, when additional silica will separate, 
and is to be filtered off. 

This final solution is nearly neutralized, as before; a little 
sodium-carbonate solution is added; it is heated to boiling, 
and an excess of a solution of calcium chloride is added. The 
precipitate of calcium carbonate and fluoride must be boiled 
for a few minutes, when it can be easily filtered and washed 
with hot water. The washed precipitate is washed from the 
filter into a small platinum dish and evaporated to dryness, 
while the filter, after being partially dried and used to wipe off 
any particles of the precipitate adhering to the dish in which 
it was formed, is burned, and the ash is added to the main 
precipitate. This, when dry, is ignited, and allowed to cool; 
dilute acetic acid is added in excess, and the whole is evap- 
orated to dryness, being kept on the water-bath until all odor 
of acetic acid has disappeared. The residue is now treated 
with hot water, digested, filtered on a small filter, washed with 
hot water, partially dried, placed in a crucible, carefully ignited, 
and weighed as CaF,. The CaF, is then dissolved in sul- 
phuric acid by gently heating and agitating, evaporated to 
dryness on a radiator, ignited at full red heat, and weighed as 
CaSO, From this weight the equivalent weight of CaF, 
should be calculated, and should be very close to that actually 
found as above, but should never exceed it. The difference 
cenerally about 1 mgm.) is due to silica which is precipitated 
with the fluoride. The percentage of fluorine is, therefore, 
always calculated from the weight of the sulphate, and not 
from that of the original fluoride. The results are very satis- 
factory. 

For other methods, as well as a complete treatise on phos- 
phates, see “The Phosphates of America,” by Dr. F. Wyatt. 





ChE ReACL, 
ANALYSIS OF LEAD AND COPPER SLAGS.* 


IN the following scheme it is assumed that the slag sample 
is vitreous, having been suddenly chilled when taken (see 
Part I, Chapter II, page 18). If such is not the case, a fusion 
will be necessary in order to effect decomposition of the slag. 
(See Part II, Chapter I, page 83.) 

For technical purposes a partial analysis will be sufficient. 
Occasionally a careful and more complete analysis may be 
required. 

The constituents of a lead slag most frequently determined 
Peni.) FeO, CaO, Pb, and Ag; MnO and ZnO are fre- 
quently important constituents; BaO, MgO, and Al,O, are 
sometimes important constituents ; Na, K, and S, whilst present 
in all slags, are rarely determined. ‘This is also the case with 
copper slags, if Cu is substituted for Pb. 


Partial Analysis of Lead Slags.—a. Determine the silica 
by treatment of 0.5 gm. with water and hydrochloric acid, 
boiling the solution for a few minutes to effect solution of all 
except silica, and filtering as rapidly as possible. (See Part IT, 
Chapter XXV, page 225.) 

6. Determine the barium by treatment of 0.5 gm. with 
water, hydrochloric acid, and a few drops of nitric and sul- 





* Whilst this scheme is to some extent a repetition of what has already been 
described in Part II, the chapter has been inserted, as the subject is of the ut- 
most importance to the lead and copper metallurgist ; and the scheme, moreover, 
illustrates the manner in which a systematic course of analysis may be built up 
from the methods described in Part II. 

307 


308 A MANUAL OF PRACTICAL ASSA YING, 


phuric acids. Evaporate to dryness, take up with water and 
hydrochloric acid, filter, wash, dry, ignite, and weigh the com- 
bined SiO, and BaSO,. The difference between the weight of 
this precipitate and the weight of the SiO,, as determined ina, 
will represent the weight of the BaSOQ,. 

c. Determine the lime in the filtrate from the SiO, and 
BaSO, as obtained in 4, according to Part II, Chapter X XIII, 
page 218. 

d. Determine the iron in 0.5 gm. according to Part II, 
Chapter XVI, page 178. 

e. Determine the manganese in 1.0 gm. by treatment with 
water, hydrochloric acid, and a few crystals of potassium 
chlorate, boiling to effect solution and oxidation of the iron. 
Treat and determine according to Volhard’s Method. (See 
Part II, Chapter XX, page 198.) 

jf. Determine the zinc in I.0 gm. according to Part II, 
Chapter XIX, page 210. 

g. Determine the lead by fire-assay, taking 5 or 10 gms, 
(see Part II, Chapter IX, page 137). Should the slag be very 
low in lead (less than 1.0%), it is difficult to find and extract the 
lead button from the slag. In this case the following method 
is frequently used: Take 5.0 gms. of slag and weigh out about 
o.I gm. of pure silver, adding it to the charge of slag and lead 
flux in the crucible. Fuse and pour the charge. The reduced 
lead will alloy with the silver, giving a button which may read- 
ily be found and detached from the slag. The increase in 
weight of the silver button represents the weight of lead in 
the 5 gms. of slag taken. 

hk. Determine the silver in 1 A. T. by crucible fire-assay, 
adding sufficient litharge and reducing agent to obtain a lead 
button of about 4 gms., which is cupelled. (Part II, Chapter 
VII, page 129.) 

In the case of copper slags proceed in the same manner, 
and determining the copper by the.colorimetric method. (See 
Part II, Chapter XIII, page 159.) 

Complete Analysis of Lead Slags.—Treat I.o gm. of the 
slag according to 6 and separate the SiO,, BaSO,, and PbSO,, 








ANALYSIS OF LEAD AND COPPER SLAGS. 309 


washing by decantation and leaving as muchas possible of the 
residue in the casserole. Extract the lead with ammonium 
acetate (see Part II, Chapter I, page 79), and filter off the SiO, 
and BaSO,. After drying, igniting, and weighing this precipi- 
tate, fuse it in a platinum crucible with sodium carbonate, and 
determine the baryta according to Part II, Chapter XXV, page 
224. The weight of the SiO, + BaSOQ,, less the weight of the 
barium sulphate as determined, will equal the weight of the 
silica. In very accurate work the silica can be determined 
directly by acidifying the filtrate from the barium carbonate 
and evaporating it to dryness, the silica being determined as 
usual. 

Nearly neutralize the filtrate from the SiO,, BaSO,, and 
PbSO, with sodium carbonate, add Io to 15 gms. of sodium 
acetate, and make a basic-acetate precipitation of the iron and 
alumina. Filter off this precipitate, wash it with hot water, 
and dissolve it in a little dilute hydrochloric acid. - Reprecipi- 
tate the iron and alumina with ammonia as hydroxides (see 
Part II, Chapter XVII, page 181 and page 184), filter, and 
wash. Dissolve this precipitate with a little dilute sulphuric 
acid, and electrolyze, using mercury for the cathode. Deter- 
mine the iron according to Part II, Chapter XVII, page 187, 
and the aluminium in the iron-free solution as a phosphate 
according to Part II, Chapter XVII, page 186. 

Combine the filtrates from the basic-acetate precipitate and 
the precipitate of hydroxides, add a little acetic acid, and boil. 
Pass a current of sulphur~tted hydrogen through the boiling 
solution for half an hour. Filter off the precipitated zinc sul- 
phide and wash with water containing H,S. (Should the slag 
contain Ni or Co—which is unusual except in rare cases of 
copper-smelting—they will be precipitated with the ZnS as 
sulphides.) The filtrate from thé precipitated zinc sulphide 
should be tested with H,S, and should a precipitate form, it 
should be filtered off and added to the first precipitate. Dis- 
solve the precipitated ZnS with hydrochloric acid, and de- 
termine according to Part II, Chapter XIX; or by precipitation 
as zinc carbonate with a solution of sodium carbonate, filtra- 


AS ee 


310 A MANUAL OF PRACTICAL ASSA YING. 


tion, washing thoroughly with hot water, and final ignition of 
the precipitate to ZnO, weighing as such. 

Boil the filtrate from the precipitated zinc sulphide, add an 
excess of bromine water, and continue to boil for half an hour. 

Filter off the precipitated manganese dioxide, wash it thor- 
oughly with hot water, boil the filtrate, and add more bromine 
water to insure the complete precipitation of the manganese. 
Dissolve the precipitated manganese dioxide with a little dilute 
hydrochloric acid, and determine the manganese according to 
any of the methods described in Part II, Chapter XX; or, the 
precipitate may be transferred to a beaker and determined by 
Williams’ Method. (See page 196.) 

Boil the filtrate from the precipitated manganese dioxide 
to expel bromine, render it alkaline with an excess of ammonia, 
and precipitate the lime as an oxalate according to Part II, 
Chapter XXIII, page 216. The precipitated oxalate should 
be dissolved’in a little dilute hydrochloric acid, the solution is 
rendered strongly alkaline with ammonia, and the lime is re- 
precipitated as an oxalate. This is necessary to insure the 
complete separation of the lime and magnesia. The lime is 
finally determined according to Part II, Chapter XXIII, pages 
217 and 218, either gravimetrically or volumetrically. 

The combined filtrates from the precipitated calcium oxa- 
late are rendered strongly alkaline with ammonia, the magnesia 
is precipitated as ammonium-magnesium phosphate, and deter- 
mined according to Part II, Chapter XXIV, page 220. 

The alkalies are determined in a separate portion of 5 gms., 
according to Part II, Chapter XX VI, page 230. 

The lead is determined in a separate portion of 5 gms. by 
treatment with water, hydrochloric acid, a few drops of nitric 
acid, and an excess of sulphuric acid, evaporation to fumes of 
sulphuric anhydride, and proceeding according to Part II, 
Chapter IX, page 139. | 

The sulphur is determined in a separate portion of from 2 
to 5 gms., proceeding according to Part II, Chapter II, page go. 

In some cases the slag may contain small amounts of Cu, 
Bi, Sb, As, and’‘Sn. In such a case it is necessary to precipi- 








ANALYSIS OF LEAD AND COPPER SLAGS. 311 


tate these elements by passing a current of sulphuretted hydro. 
gen through the filtrate from the SiO,, BaSO,, and PbSO.,. 
The precipitated sulphides are filtered off, the precipitate is 
washed with water containing H,S, and the different metals in 
this precipitate may be separated and determined according to 
the methods described under the different metals. The filtrate 
from the precipitated sulphides is boiled, and the sulphur oxid- 
ized with bromine or potassium chlorate before proceeding 
with the analysis. 

The same method will answer for copper slags, except that 
in this case the copper and other metals of the sulphuretted- 
hydrogen group will have to be precipitated with H,S, the pre. 
cipitated sulphides being filtered out before proceeding with 
the analysis. The precipitated sulphides may be dissolved in 
nitric acid, and the copper determined colorimetrically accord- 
ing to Part II, Chapter XIII, page 159. 

A method preferred by some chemists for slags containing 
baryta is as follows: Obtain the SiO, and BaSO, by treat- 
ment with acids, filtration, etc., as above. Weigh the com- 
bined SiO, and BaSO,, and then expel the silica as a fluoride 
by treatment with hydrofluoric and sulphuric acids, repeating 
the treatment until the weight is constant. The loss in weight 
equals the silica, and the final weight equals barium sulphate, 
which should be calculated to baryta (BaO). 


CHARTER AX X. 


ASSAY OF GOLD-ALLOYS CONTAINING SILVER AND 
PLATINUM. 


PLACER gold, bullion, and old jewelry sometimes contain 
platinum when the ordinary method of assay cannot be 
adopted, 

For the following methods for the assay of such material 
the author is indebted to J. B. Eckfeldt,* Assayer of the U.S. 
Mint, Philadelphia. 

Gold.—If the alloy does not contain more than 3 per cent 
of platinum the gold can be determined as in the ordinary gold- 
bullion assay (see page 246). Should the percentage of plati- 
num be greater than 3, a smaller proportion of the alloy should 
be taken for assay, and sufficient pure gold (the proof gold) is 
added to bring the weight up to 1000. For example, suppose 
the alloy contains about 6 per cent of platinum; then we would 
weigh out 500 parts (= 0.25 gm.) of the alloy, add 500 
parts (= 0.25 gm.) of pure gold, add 2000 parts (= I. gm.) of 
silver, 5 gms. of lead, a little copper, and proceed in the usual 
manner, cupelling, rolling into a cornet, and parting in nitric 
acid. The cornet is boiled in nitric acid (32° Beaumé) until all 
action of the acid apparently ceases, and is then boiled for 
twenty minutes in fresh nitric acid (32° Beaumé). Where there 
is a large excess of gold and silver present the platinum dis- 
solves in the nitric acid. A proof, made up as nearly like the 
bullion under examination as possible, should be run with each 
set of assays, as in the gold-bullion assay. This is important, 
as there is invariably some platinum and silver remaining with 
the gold. Whatever surcharge of platinum and silver the proof 
shows is to be deducted from the weight of the regular assay. 

Platinum.—To determine the platinum make a second 





* The methods are due to Dr. Cabell Whitehead. 
31Ia 


ALLOYS CONTAINING SILVER AND PLATINUM. 3116 


assay exactly as for gold, but part in concentrated sulphuric 
acid in place of nitric acid. Thecornet should be boiled in the 
«concentrated acid for twenty minutes, when the acid is poured 
off and fresh acid is added, in which the cornet is boiled 
twenty minutes. The resulting cornet is washed, dried, 
annealed, and weighed, the weight being gold and platinum. 
Some silver invariably remains with the cornet, so it is neces- 
sary to run a proof made up exactly as the regular assay and 
along with it. Whatever gain in weight (above the weight of 
gold and platinum taken) the proof shows is to be deducted 
from the weight of the cornet obtained in the regular assay. 

Silver.-—-The wet method is the only one which is reliable 
for the determination of the silver. 

One of the following methods may be used: 

first Method.—Weigh out 500 parts of the alloy (= 0.25 
gm.), enclose in 2.5 to 3 gms. of assay lead, place on a hot cupel, 
and just fuse. Remove from the furnace, cool, detach from 
the cupel, and dissolve in nitric acid (26° Beaumé), adding to 
the acid the proper quantity of pure silver to bring the total 
parts of silver present up to 1000 (=0.5 gm.). For example, 
‘suppose the approximate fineness of the bullion, as determined 
by preliminary assay, to be: gold 700, silver 150, platinum 50, 
and base 100, as 500 parts of the alloy were taken, the amount 
of silver present would be 75; hence 75 + 925 = 1000; or it is 
necessary toadd 925 parts of silver. In making the preliminary 
assay, the quantity of platinum present may be judged approxi- 
mately by the color the platinum imparts to the nitric-acid 
solution. The assay is now proceeded with exactly as in the 
determination of silver in silver bullion (see page 240), allow- 
ance being made, by deduction from the result, for the 925 
parts of silver added. 

Second Method.—TYhis method is more accurate than the 
first, and is to be preferred in close work. Fuse a small 
quantity of potassium cyanide (pure and free from sulphides 
and sulphates) in a small porcelain crucible, drop into the fused 
mass 2 to 3 gms. of pure cadmium (or zinc), add the 500 parts 
of alloy, and when fusion is complete pour out ona cold slab. 





311¢ A MANUAL OF PRACTICAL ASSAYING. 


Wash the button to free it from cyanide, dissolve it in nitric 
acid (26° Beaumé), adding the proper quantity of silver to bring 
the silver present up to 1000 parts, and proceed to determine 
the silver in the usual manner by means of standard salt solu- 
tion. 

Alloys containing Iridium and Osmium.—Occasionally 
alloys containing these rare metals will be encountered. In 
this case the iridium and osmium will be found with the gold 
cornet, and may be separated by dissolving the cornet in aqua 
regia, evaporating until the nitric acid is expelled, diluting with 
distilled water, and filtering off the iridium and osmium, which 
may be dried and weighed. 

Ores.—For the determination of gold and platinum in ores 
the ore may be treated exactly as in the gold assay (see page 
258), the resulting lead buttons being cupelled. The resulting 
button will contain the gold, platinum, and iridium and osmium, 
should these metals be present. After weighing, the buttons 
may be treated exactly as in the case of alloys. | 


= Cie? 
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b TYR 


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$4: 


PART IV. 


CT Ase ade 
THE WRITING OF CHEMICAL EQUATIONS. 


IN order to work intelligently and to be able to calculate the 
results of an analysis by stoichiometry, the chemist should not 
only thoroughly understand the reactions which take place at 
each step in the analysis, but should be able to construct the 
equation which represents the reaction. 

A chemical equation is the expression in symbols or for- 
mulz of the changes which elements or chemical compounds 
undergo when subjected to chemical or physical influences. 
As all matter is indestructible, these expressions of change 
must necessarily be equations. A chemical equation differs 
from a mathematical equation inasmuch as it cannot be ac- 
cepted as true until verified by experiment; nor can it be 
treated in the same way as a mathematical equation, as, for 
example, equal amounts cannot be subtracted from either side 
of the equation and leave it true. 

There are three classes of chemical equations: Synthetical, 
Analytical, and Metathetical. : 

Synthetical Equations are those representing the union 
of elements or compounds: 


2H+0= H,O, 
CaO + CO, = CaCO,. 


312 





° 





THE WRITING OF CHEMICAL EQUATIONS. Sie: 


Analytical Equations are those representing the separa- 
tion of a compound into its constituents : 


H,O + electric spark = 2H-+ O, 
CaCO, + heat = CaO + CO,,. 


Metathetical Equations (equations of interchange) are 
those representing the interchange of elements or radicals, and 
the formation of new products: 


AgNO, + HCl = AgCl+ HNO,,. 


The last claim attention most frequently, and of these the 
equations of oxidation and reduction are the most interesting: 


3MnO + Mn,O, = 5Mn0O,,. 


The laws governing chemical interchange have not been 
fully determined, but the two following exert an important 
bearing on the results: 

Ist. When a compound can be formed which is insoluble 
in the menstruum present, this compound separates as a pre- 
cipitate. There are exceptions to this rule. 

2d. When a gas can be formed, or any substance which is 
volatile at the temperature at which the experiment is made, 
this volatile substance is set free. 

The interchange effected is a:ways on terms regulated by 
the quantivalence of the elements or radicals involved. For 
example, a monad element or radical can replace another 
monad element or radical only atom by atom. To effect an 
exchange between a monad element or radical and.a dyad ele- 
ment or radical, two atoms of the monad are required for each 
atom of the dyad: 


BaO -- 2HCI = BaCl, + H,O. 


In writing an equation, first place down the symbols or 
formulz entering into the equation in the first member of the 
equation, and write the plus sign between them. Now write 


314 A MANUAL OF PRACTICAL ASSAYING. 


the symbols or formulz of the products resulting from the 
reaction as the second member of the equation. Now adjust 
the factors of the symbols or formule so that the interchange 
will result in a true equation. ‘The data for the second mem- 
ber of the equation is either a matter of memory or else must 
be obtained by actual experiment. Very frequently a knowl- 
edge of the conditions which affect an interchange will enable 
one to predict by equations what products will be formed. 
The adjustment of the factors is the important point, and is 
best illustrated by the following examples: 


EXAMPLE No. I. Required the construction of an equa- 


tion showing the oxidation of ferrous chloride by potassium 
bichromate. i 

The compounds which enter into the reaction are FeCl,, 
K,Cr,O,, and HCl. The compounds formédvare ei ee 
Cr Gi and @. 

As oxidation signifies an increase and reduction signifies 
a decrease in the quantivalence of an element, the oxidizing 
agent, in exerting its influence, decreases in quantivalence, 
whilst the substance oxidized experiences a corresponding 
increase in its quantivalence. Writing out the equation and 
leaving spaces for the factors, we have 


FeCl,+ K,Cr,O,-- HCl= Fe,Cl,-+ KCl-+ Cr,Cl,+ H,O. 


Now the iron passes from the dyad state to the tetrad 
state, thus: 2FeO + O = Fe,O,. Hence twoureureqimes 
one O. 

One K,Cr,O, yields 30, thus: Cr,O, = Cr,O,+ 30. Hence 
6 of the ferrous compound need 1 of the bichromate. Making 
the adjustment, we have 


6FeCl, + K,Cr,O, + HCl = Fe,Cl, + KCl Crcl, 2 Ho. 


Now if we arrange the factors for the other compounds 
according to the prescribed conditions of the solution (acid, 
alkaline, or neutral), we have 


6FeCl, + K,Cr,O, + 14HCl = 3Fe,Cl, + 2KC1+ Cr,Cl,+ 7H,0. 


eas.) 








THE WRITING OF CHEMICAL EQUATIONS. 315 


Testing to see if this is a true equation, we have 
In the In the 


First Member. Second Member. 
[Svcs SUS a gaan Se aee SB ae 6 6 
ASS 5 tyke, SRS RO aa 26 26 
IC ee otk O oiciehe wa 2 2 
ea ey 7 7 
LS ell aS adage rare a 14 14 
BO ee Stik eee ewes 2 2 


The factors all balance, and hence the equation is correct. 

EXAMPLE NO. 2. Required to construct an equation 
showing the oxidation of antimonous chloride to antimonic 
chloride by potassium permanganate. 

The compounds which enter into the reaction are Sb,Cl,, 
pew... and) HCl. . The compounds formed are Sb,Cl,,, 
mC MnCl, ahd H,O. 

Writing out the equation as before, and leaving spaces for 
the factors, we have 


Sb,Cl,+ K,Mn,O,+ HCl= Sb,Cl,,+ KCI+ MnCl,+ H,O. 


Now the antimony passes from the triad to the pentad 
state, thus: 
Sb,O, + 20 = Sb,O,. 
One K,Mn,0O, yields 50, thus: 
Mn,O, = 2MnO + 50. 
Hence 1 of the antimonous requires 20, or 5 of the antimon- 


ous requires 100, or 2 of the K,Mn,O,. Making the adjust- 
ment, we have 


sSb,Cl, + 2K,Mn,0,-- HCl = 
55b,Cl,, + 4KCl + 4MnCl,+ H,O. 
Arranging the factors for the HCl and H,O, we have 


5D, C1, as 2K,Mn,O, + 32HCl = 
5Sb,Cl,, + 4KCl + 4MnCl, + 16H,O. 


; La oe 


316 A MANUAL OF PRACTICAL ASSA YING. 
Or the equation may be written 
5SbCl,+ K,Mn,O,+16HCI1 = 5SbCl,+ 2KCl+ 2MnCl,+ 8H,O. 


Testing to see if this is a true equation, we have 


In the In the 
First Member. Second Member, 
NS) AP Arp raisa a cyseine 1N 5 
OF SNP seit, Hewes 2h 31 
OAR) Meer ASP da most, 68'S! 8 
Ne esta a: hare alee nitreae SARL 16 


The factors all balance, and hence the equation is correct. 

This method is due to Prof. Elwyn Waller, and is the 
method taught by him in the Columbia College School of 
Mines. | 

The following excellent method of constructing equations 
is due to Otis C. Johnson.* According to Mr. Johnson’s defi- 
nition of donxd, by the bond of an element is meant the amount 
of oxidation it is capable of sustaining, and hence he defines 
bond as an oxidizing force. When an element has no oxidiz- 
ing power it has no bonds. When an element is a reducing 
agent its bonds are negative. 

He gives the following rules for ascertaining the bonds of 
an element: 

Ist. Hydrogen in combination has always one bond, and is 
always positive. (H1‘.) 

2d. Oxygen always has two bonds, and they are always 
negative. (O-%) 

3d. Free elements have no bonds; thus metallic iron (Fe°). 

4th. The sum of the bonds of any compound is always 
equal to zero. Thus 


Fl Mn,* XIV Ge ai O. 





* Negative Bonds and Rules for Balancing Equations, Chemical News, 
1880, Vol. XLII, p. 51. 


THE WRITING OF CHEMICAL EQUATIONS. 317 


sth. Acid radicals are always negative. Thus 
Pee = OM eand) | Me, PO.)> = O, 


6th. Metals in combination are usually positive. The 
most prominent exceptions to this rule are their compounds 
with hydrogen. Thus 


1 (7 +11 -TII UI 
Seiad ae anger se pera 


As the oxidation of one substance involves the reduction 
of some other substance, the number of bonds gained by the 
one is lost by the other. 

From the above a rule for writing the equations of oxida- 
tion and reduction is derived, provided the resulting products 
are known. The following is the rule: 

The number of bonds changed in one molecule of each 
shows how many molecules of the other must be taken. The 
words each and other refer, respectively, to oxidizing and re- 
ducing agent. 

EXAMPLE No. 3. Applying this method to the problem 


FeCl, + K,Cr,O, + HCl = Fe,Cl, -+ KCl-+ Cr,Cl, + H,O, 
we find that 


rein tnenirst member has 12 bonds; (K,*% Cr,*27 ©," =v.) 
Cr, in the second member has 6 bonds. (Cr,+¥! Cl,~ 4.) 
ieecce Oo tience OleCl. 
Fe in the first member has 2 bonds; (Fet™ Cl,-%.) 
Fe in the second member has 3 bonds. (Fe,* ¥! Cl,- V4) 
oie tee lence nN Gr... 


EXAMPLE No. 4. Applying this method to the problem 
Sb,Cl, + K,Mn,O, -+ HCl = Sb,Cl,, + KCl + MnCl, + H,O, 
we find that 


Mn, in the first member has 14 bonds; 

Mn, in the second member has 4 bonds. 
Poss 10). Lience JoobU ly oms5ob.Cl. 

Sb in the first member has 3 bonds; 

Sb in the second member has 5 bonds. 
Gains—2- ‘Hence, 2 keihin: 


318 A MANUAL OF PRACTICAL ASSA YING. 


EXAMPLE No. 5. Required to construct the equation for 
the oxidation of ferrous sulphate to ferric sulphate by potas- 
sium permanganate. | 

The compounds entering into the reaction are K,Mn,O,, 
FeSO,, and H,SO,. The products formed are Feta 
K,SO,, MnSO,, and H,O. Writing the equation and leaving 
spaces for the factors, we have 


FeSO,+ K,Mn,0O,+ H,SO, = 
Fe,(SO,), + K,SO,-+ MnSO,+ H,O. 

Mn, in the first member has 14 bonds; 
Mn, in the second member has 4 bonds, | 

Loss = "10" WFrerice/ 10 eas 
Fe in the first member has 2 bonds; 
Fe in the second member has 3 bonds, 

Gain =1. Hence TK Nines 


Hence for the completed equation we have 


10FeSO, + K,Mn,O, + 8H,SO, = 
5Fe,(SO,), + K,SO, + 2MnSO, + 8H,0. 


EXAMPLE No. 6 Required to construct the equation 
showing the oxidation of oxalic acid to carbonic acid by potas- 
sium permanganate. 

The compounds entering into the reaction are H,O, C,O,, 
K,Mn,O, and H,SO,. The compounds formed are CO,, 
H,O, MnSO,, and K,SO,. Writing the equation and leaving 
space for the factors, we have 


H,O, C,O,+ K,Mn,O,+ H,SO, = 
CoO,+ K,SO,+ MnSO,--) He. 

Mn, in the first member has 14 bonds, 
Mn, in the second member has 4 bonds, 

Loss. 10. Hence 10H Ce 
C, in the first member has 6 bonds ; 
C, in the second member has 8 bonds, 

Gain =2. Hence 2K,Mn,O,. 


THE WRITING OF CHEMICAL EQUATIONS. 319 


Wilting the equation and adjusting the factors for the 
H,SO, and H,O, we have 


10H,C,O, + 2K,Mn,O, + 6H,SO, = 
20CO, + 2K,SO, + 4MnSO,-+ 16H,0O. 


Or the equation may be written (dividing the factors of each 
member by 2), 


511,C,0, + K,Mn,O, + 3H,SO, — 
_10CO, + K,SO,-++ 2MnSO, + 8H,O. 


Testing to see if this is a true equation, we have 


In the In the 
First Member. Second Member. 
eis ia tes asc piceins LQ 16 
3.5 4) CARO ae eee 10 10 
hoo 4 ae Paribas «3. 40 
oo VORA AEE eee 2 2 
Mn 2 2 
te oy atin ais a 550-0. « 3 3 


Hence it is a true equation. 

EXAMPLE No. 7. Required the construction of an equation 
representing the oxidation of MnSO, by K,Mn,O,. The com- 
pounds entering into the first member are Mn5SO,, K,Mn,O,, 
and H,O. Those entering into the second member are MnO,, 
K,SO,, and H,SO,. Writing the equation and leaving spaces 
for the factors, we have 


MnSO,-+ K,Mn,O,+ H,O = MnO,+ K,SO,-+ H,SO,. 
By the first method we have 
MnO-+ O = MnO, 
Hence 1MnO requires 10. 
Mn,O, = 2MnO, + O,. 


320 A MANUAL OF PRACTICAL ASSAYING. 


Hence 1K,Mn,O, yields 30. Now as 1MnO requires 10 and 
1K ,Mn,O, yields 30, we find that 1K,Mn,O, will oxidize 
3MnSO,. Hence the equation 


3MnSO, + K,Mn,O, + 2H,O = 5MnO,+ K,SO, + 2H,SO,. 


By the second method, 
Mn in the first member has 2 bonds; 
Mn in the second member has 4 bonds. 
Gain =\2.. 7 Hence 2K Mine 
Mn, in the first member has 14 bonds; 
Mn, in the second member has 8 bonds, 
Loss =6. Hence 6MnSQ,. 


Hence the equation: 


6MnSO,-+ 2K,Mn,O, + 4H,O = 1oMnO,-+ 2K,SO,-+-4H,SO,, 


which may be written as above. 


Clg ra ii8 ie Ake a 
STOICHIOMETRY. 


STOICHIOMETRY is the arithmetic of chemistry. All that 
is required to solve the different stoichiometrical problems is a 
knowledge of chemical reactions and the writing of chemical 
equations, and a knowledge of the principles of arithmetic. 
Most of the problems which arise in the course of chemical 
analysis may be solved by simple proportion. 

The solution of the different problems is best illustrated by 
the following examples: 

Calculation of Percentage from Weight.—EXAMPLE 
No. 1.—Five grammes of lead ore were taken for assay. A 
lead button weighing 2.466 gms. was obtained. What is the 
percentage of lead in the ore? 


5.0 (weight taken) : 2.466 (weight found) :: 100: 4 
mem Dercentave required = 40/32. 


EXAMPLE No.2. Inthe assay of a zinc ore 1.521 gms. were 
taken and 0.3246 gm. of zinc was obtained. What is the 
percentage of zinc in the ore? 


Bae tO; 3240.2. 100. ht fe ea 2 AS 


Calculation of Percentage Composition from Chemical 
Formula.—The relation existing between the combining 
weights and the percentages of the constituents of a chemical 
compound is best expressed by a simple proportion in which 
the first two terms are the combining weights of these con- 
stituents and the last two terms the corresponding percentages. 

321 


322 A MANUAL OF PRACTICAL ASSAYING. 


EXAMPLE NO. 3. The formula for barium chloride is 
BaCl, , 2H,O; required the percentage of Ba. 
We have the proportion 


243.6.2:130,0 210022 ° 


or, the combining weight of the compound is to the combining 
weight of the constituent whose percentage is required as 100 
per cent is to the percentage required. 

In like manner the solution of the following proportions 
determines the percentages of Cl and H,O, respectively: 


243.94 78 3: 100% 2; 
243.8 396.53 1003 4, 


Ans. Ba= 6.11%; Cl = 20.12%; 1 Oe. 


EXAMPLE No. 4. The formula for magnesium sulphate is 
MgSO,, 7H,O; required its percentage composition in MgO, 
SO,, and H,O. We have the following proportions: 


246: 402: 100: #3) 4 =a 
24052 803 100 city ae eee 
246 : 126 23.100.) 45) “4 eee 


Ans. MgO = 16.264; SO, = 32.52%; iO = sirens 


EXAMPLE No. 5.—In the analysis of a limestone I.0 gm. 
was taken for analysis, and a precipitate of CaSO, weighing 
0.812 gm. was obtained. A precipitate of Mg,P,O, weighing 
0.385 was also obtained. What is the percentage composition 
of the limestone in CaO and MgO? 


136:50::0.812:2; x =0:334254 = weight of Ga ean 
1.0 3 0.334254 3:°100 243 (4) 2)33.445 Oa 

222 : 80 ::0.385:#; +=0.139 = weight af MgO; and 
1.0: 0.139?: 100:%; # = 13.90% MgO. 





STOICHIOMETRY. 323 


EXAMPLE No. 6. Required the percentages of CaCO, and 
MgCO, corresponding to the percentages of CaO and MgO in 
Example No. 5. 


Bor 100 34.40.12 7) 4 = 60.00%, CaCO. 
BOrnOA 2 603.00 t43 4 20.10% MeCO.. 


EXAMPLE No. 7. How many grammes of oxygen will it 
take to convert 50 grammes of carbon into carbonic acid gas? 

As each part of carbon requires two parts of oxygen, we 
have the equation 


Trea a OOo a a 123.89 Ging, 


EXAMPLE No. 8. How many grammes of silver will 5 
grammes of sodium bromide precipitate from a solution of 
silver in nitric acid? From the equation, 


AgNO, -+ NaBr = AgBr-+ NaNO, 


we see that 1 part of NaBr will precipitate 1 part of silver; 
hence the proportion 


Tonmeon: 5: 25) ta 52427 ons. Ag, 


The Calculation of Factors.—In gravimetric analysis the 
substance to be determined is either separated in a state of 
purity and its weight is obtained directly (see Examples No. 1 
and No. 2), or by the operations of the analysis it is obtained 
and weighed as a constituent of a compound whose formula is 
known (see Examples No.5). By the preceding rule the weight 
of the constituent sought may be calculated. In Part II factors 
have been given under the different determinations for the cal- 
culation of the weight of the constituent sought from the weight 
of the compound obtained in the analysis. These factors are 
derived as follows: 


324 A MANUAL OF PRACTICAL ASSAYING. 


EXAMPLE No. g. Required the factor for the calculation 
of Sin BaSO,. | 
As in Examples No. 3 and No. 4, we have the equation 


VaR AN he 4 Sol Ee ea gee Mame AN AGO SS 


which is the factor for S in BaSO,,. 

EXAMPLE No. 10. Required the factor for the calculation 
of Sn in SnO,. 

We have the proportion 


TGO'TIO Crete eerie Oo 


which is the factor required. 7 
EXAMPLE No. 11. In the course of an analysis nitrogen is 
converted into (NH,Cl),PtCl,, which precipitate is ignited and 
the weight of the resulting platinum is obtained. What factor 
will give the weight of the N? 
As one part Pt is combined with 2 parts N, we have the 
proportion 


197 : 28:33 Tt: 55 94. — 0. 142i 


which is the factor required. 

EXAMPLE NO. 12.—What are the factors for MgO and P 
in Mg,P,O,? Ans. MeO sanae 0.36036. 

P aie see yeaes 

The Calculation of Formulz.—The deduction of an em- 
pirical formula from the percentage composition is the reverse 
of the process of calculating percentage composition from for- 
mule. 

Three cases may arise. 

First Case.-—From the percentages of single elements in 
compounds. 





STOICHIOMETR ¥. 325 


EXAMPLE No. 13. Upon analysis a substance was found 
to contain the following parts in 100: 


aU A ee Ne Ng 4 Nai al e'ar se ete e tie 2.04 
Us 0 5 Bc Ry EPH AUN an ae earners 32.65 
2 5 8 ocd SBR Aes RR ag NSE EE RD 65.31 


What is the formula of the substance? 
Dividing the percentage of each element by its atomic 
weight and reducing the quotients, we have 


| oy yg 2.004 + I1=2.04+102=2 
eae 32.65 + 32— 1.02 + 1.02=I1 
O22 Sao 65.31 + 16= 4.08 + 1.02 =4 


Hence the formula is H,SO,. 
EXAMPLE No. 14. Upon analysis a compound yielded the 
following percentages: 


ON ert I eee) okt 5.cihe aye 52.20 
RM Regs avy g'. scje o's. sats’ s S65 
CO) ha St Re ae 35.00 


What is its formula? 


ee 5 220 12 = 4 35 4.35 1 
ph la Nee 13.05 + I= 13.05 + 4.35 = 3 
a 35.00 + 16 = 2.187 + 4.35 =0.502 


Hence, allowing for error in the analysis, the formula is prob. 
ably C,H,O, which is the formula for ethyl alcohol- 

Second Case.—From the percentages of groups of elements 
in compounds, isomorphous constituents being absent. 

It is general in the analysis of oxygen salts to calculate the 
percentages of oxides and water equivalent in quantity to the ele- 
ments. The results of an analysis being stated in this manner, 
the percentages of the different elements may readily be. com- 
puted, and from these percentages the empirical formula may be 


326 A MANUAL OF PRACTICAL ASSAYING. 


calculated by the preceding rule. The same result may be 
attained by the following shorter course. 

EXAMPLE NO. 15.—-Upon analysis a substance was foun 
to have the following percentage composition: 


La 4 Ge AMAA Gey eer eS 51.20 
oO 5 Se MEE EAE OTE heals Py OKeT) LA 22558 
MeO oie ee Bae aie ie eee 16.24 


What is its chemical formula? 

Dividing each constituent by its molecular weight and re- 
ducing the quotients to their simplest relations in whole num- 
bers, we have 


LOS a, 51.20 + 18 = 2.844+. +0.4006 = 7.09 | 
SO,...... --32.53 + 80 = 0.40066+ + 0.4006 = 1.00 
NIG Ree 16.24 + 40 = 0.4006 ~~ 0.4006 = 1.00 


Hence, allowing for error in the analysis, the probable rational 
formula is MgOSO,,7H,O. Rearranging the order in which 
the symbols of the elements stand, we have the strictly em- 
pirical formula MgSH,,Q,,. 

Having obtained the empirical formula of a compound, its 
rational formula may be obtained by making any reasonable 
supposition regarding its chemical constitution and arranging 
the atoms conformably. For example, in the above case, 
allowing 10 to the Mg we have 100 remaining and 14H. 
Assuming that the H is combined with O as water of crystalli- 
zation we have 7H,O, which still leaves 30 to be combined: 
with the S as SO,. Hence the formula MgOSO,, 7H,O, or 
MgSO,,7H,0O. 

Third Case.—From the percentages of groups of elements 
in compounds, isomorphous constituents being present. 

In the deduction of formula it should be remembered that 
closely related radicals may replace each other in all ‘propor- 
tions. This is especially true of the basic metals. Generally, 
elements of like valence are found replacing one another; but 





STOICHIOMETRY. 327 


in some cases equivalent amounts of elements having different 
valence replace each other. 

EXAMPLE No. 16. Penfield* found by analysis of triphy 
lyte the following composition: 





LLCS. Aral aetna ty Sa ear ena 44.76 

eS ES Ge Ae Sg ae 26.40 

Pee R Ue cea RAT Vrs Ah bia ne cba ae 5 17.84 

UO eS es a ar ee 0.24. 

"WEY se eae TT I eI Peer Sea ara 0.47 

RR yas Viele ce 36 eed Ae ao be eh 9.30 

Pee Men Ore OU Vis ra hve ee obra Sa 0.35 

PANES Tyla ey a0 os 4 Ri oa lek oA « 0.42 

99.84 

What is the formula for the mineral ? 

Molecular Weights. Mol. Ratio. Atomic Ratio. 
eee 4476 = 142 = 315 XK 2= P ° 630 
eee 20.40 —=- 72 — 1366 ew OU) 
DN) Soka a" 17.84 + 71 =.251 Ni T 2 51 ae 
CLG a eee 0.24 + 56 = .004 Sea COA ee el 
Be i. 0.47 + 40=.012 mores 1) Bed ON 
LAL EIS Pee Pg iat 310 2 iY 824.) R’ 6 
Meat) 2h cil 25 evans 02° 005 X 2.— Na ane oe aoe 
ls @ Magar asa 0.42 Or 725825 


In this case the small amount of water may be disregarded. 
The atomic ratio column, with the adjoined symbols, is the 
empirical formula. 

As is to be expected, when isomorphous constituents are 
present, the number of different atoms are not in any simple 
ratio. Hence it remains to unite the atoms of such elements 
as are supposed to be capable of mutually replacing each other, 
and ascertain if the numbers thus obtained are in any simple 
proportion. For this purpose let R” represent one atom of 
any dyad basic metal and R’ one atom of any nomad basic 


*Fresenius, Quantitative Chemical Analysis, p. 847. 


i a SG eee 


328 A MANUAL OF PRACTICAL ASSAYING. 


metal present. The atomic ratio, obtained as above, is ex- 
pressed by the formula R’’,,.R’gs,P 4.002008, OF dividing by 630, 
almost exactly by R”R’PO,, which is equal to 


JO dt 
(POY ZO>R” 
Soe R’ 


anhydrous normal lithium phosphate in which iron is partially 
replaced by manganese, magnesium, and calcium; and lithium 
to a slight extent by sodium. 

Omitting oxygen from the above calculation, we have 
R’R’P. Referring to the percentage computation, it is seen 
that two P require five O; two R’ one O;3 one] saneus 
Doubling R’’R’P and appending to each constituent the re- 
quired oxygen atoms, we have R”,O,R’.OP,0, = RR PO 
= R’R’PO,, as betore: 

EXAMPLE No. 17. A lead blast-furnace slag upon analysis 
gave the following percentage composition : 


SIO Er eter ty eee ee ee i os 36.0 
FeO. :ciche cee etece opine 4 bie area Cale enn 28.8 
CaQ bein soca selene aes cleles sie 28.0 
AL OS aU ietiste sts el sre wie ot Ceieeee 7.6 

100.4 


Required a formula which represents the composition ? 


Molecular Ratio. Atomic Ratio. 


rere Bag rh 306.0+ 60=. SiO seo 
MeQiiaga. 28.8 +. 92:== 4.7 Pea R” 
Car han 28.0. =+-1;}0 85 Cae 9 
ALO ice. 7.6 + 102 =.075 Al (eigehe aaa. 


Dividing this atomic ratio by 0.15, we obtain the formula 
R,’RSi,, or (RO,),(R,/0,)(Si0,), = (RO) ,(Ry’”0,)(SiO,,). 

Caiculations involved in the Making-up and Use of 
Volumetric Solutions.—EXAMPLE No. 18. Required the 


STOICHIOMETRY. 329 


amount of sodium bromide necessary to add to water in order 
to make a solution of which 1 cc. will exactly Peeps 0.01 
gm. of silver? 

From the equation 


AgNO, + NaBr = AgBr + NaNO, 


we see that 1 atom of Br precipitates 1 atom of Ag. Hence 
the proportion 


FOS 102) :3 0.0L 24; <2 = 0.000537; 


108 being the atomic weight of Ag and 103 being the molecular 
weight of NaBr. Consequently if 1000 cc. is the quantity of 
standard solution required, weigh out 9.537 gms. of pure dry 
sodium bromide, dissolve, and dilute to 1000 cc. with distilled 
water. 

EXAMPLE No. 19. Upon trial of the sodium-bromide solu- 
tion as made up in the preceding example each cc. was found 
to only precipitate 0.00956 gm. of Ag. Required the amount 
of the salt which should be added to 1000 cc. so that each cc. 
will precipitate exactly o.o1 gm. of Ag? As 9.537 gms. of 
NaBr were taken in making up 1000 cc. of the solution, we have 
the proportion 


0.00956 : 0.01 :: 9.537: 4%; += 9.9759 gms., 


which is the amount of sodium bromide which should have 
been taken. Hence 9.9759 — 9.537 = 0.4389 gm. of NaBr to 
be added to each 1000 cc. of the solution to make it normal. 

EXAMPLE No. 20. An acid solution of ferrous sulphate 
contains 0.215 gm. of iron. How many cc. of a solution of po- 
tassium permanganate containing 0.01 gm. of K,Mn,O, in each 
cc. will be required to convert the ferrous sulphate to ferric 
sulphate? 

By reference to the equation representing the oxidation 
{see Part IV, Chapter I) we see that 1 molecule of K,Mn,O, 
will oxidize 10 molecules of ferrous iron. The molecular 


330 A MANUAL OF PRACTICAL ASSAYING. 


weight of 10Fe is 560 and the molecular weight of 1kK,Mn,O: 
is 316.2; hence 


560 39310.2: 2 0-295 “oro eer = One 
Now, as each cc. of the solution contains 0.01 gm. K,Mn,O, and 


O.121 
efi 12.14 cc. of 
0.01 





0.1214 gm. are required, we will require 


the solution. 

EXAMPLE No. 21. A solution of potassium permanganate 
was found to be of such a strength that each cc. was equivalent 
to (would oxidize) 0.0093 gm. of iron. What is the value of 
the solution in terms of manganese ? 

By reference to the equation for the precipitation of man-. 
ganese by potassium permanganate (see Part IV, Chapter I). 
we see that 1 molecule of K,Mn,O, will precipitate 3 atoms of 
Mn, whilst each molecule of K,Mn,O, will oxidize 10 molecules. 
of Fe. Hence the proportion 


5600: 105 330.0003 43 94 =O.Gceea, 


560 being the molecular weight of 10Fe and 165 being the 
molecular weight of 3Mn. 

EXAMPLE No. 22. Having prepared and standardized the 
following solutions, required the equivalent of the iodine solu- 
tion in terms of sulphur: 

A solution of potassium bichromate of which 1 cc. = 0.005 
zm. Fe. 

As I equivalent of K,Cr,O, oxidizes 6 equivalents of Fe, we: 
have the proportion 


336 : 294.5 ::0.005:4; +4 =0.004382; 


or, each cc. of the bichromate solution contains 0.004382 gm. 
Olt er. 3 

A solution of iodide of potassium was prepared by dissolv- 
ing I gm. of pure KI in 300 cc. of water and 5 cc. of HCl. To 
this solution 25 cc. of the bichromate solution was added. 


STOICHIOMETRY. 331 


Now, as 294.5 parts of K,Cr,O, will liberate 761.1 equivalents. 
of iodine (see Part II, Chapter II), we have the proportion 


moe etOlils 10-1005 5.341, 9 4 == 0.28312; 


or, the 25 cc. of bichromate will liberate 0.28312 gm. of iodine. 

Upon the addition of sodium-hyposulphite solution to this 
solution containing 0.28312 gm. of free todine, 24 cc. were re- 
quired to decolorize the solution. Hence each cc. of the hypo- 
sulphite solution contains sufticien NaHS,O, to react on 
0.0118 gm. of iodine. 

Ten cc. of the hyposulphite solution were then drawn off, 
diluted with water, a few drops of starch solution were added, 
and the iodine solution to be standardized was run in until the 
blue color was destroyed, 20 cc. being used. 

As 10 cc. of the hyposulphite solution would react on 0.1180 
gm. of iodine, each cc. of the iodine solution contains 0.005¢ 
em. of iodine. From the equation 


H,S+2I1=2HI+S5S 
we have the proportion 


253-7 = 32 ::0.0059: 4; %# = 0.000744; 


or, each cc. of the iodine solution is equivalent to 0.000744 
on. 

Calculation of the Results of Indirect Analyses.—Ex- 
AMPLE NO. 23. In the analysis of a mineral containing both 
calcium and strontium the Ca and Sr were separated, converted 
into CaCO, and SrCO,, and the mixed carbonates were weighed. 
together. Subsequently the carbonic acid was determined. 
The weight of the mixed carbonate was 0.935 gm. and the 
weight of the carbonic acid which the mixed carbonates con- 
tained was 0.362 gm. Required the corresponding weights of 
CaO and SrO. | 


Mol. Wt. COs. Mol. Wt. SrCOs. Wt. COs. ; 
44 ; 147.5 TUG RG SPS gee Nae i ie deh Gen be ee 


332 A MANUAL OF PRACTICAL ASSAYING. 


If, therefore, the whole of the carbonic acid were combined 
with strontia, the weight of the carbonate would be 1.21352 
ems. The difference (1.21352 — 0.935) =0.27852 is propor- 
tional to the calcium carbonate present, which is calculated 
as follows: 

The difference between the molecular weight of SrCO, and 
the molecular weight of CaCO, (47.5) is to the molecular weight 
of CaCO, (100) as the difference found is to the calcium car- 
bonate contained in the mixed salt; or, 


47.5.2 100 33.0.27852.: 23) 4 = Oreos 


Therefore the mixture contains 0.5864 gm. CaCO, and 0.3486 
Sino COs 

Calculations involved in the Analysis of Gases.—Reduc- 
tion of the Volume to what it would be in the Normal State.— 
The tension, and therefore the volume of the gas, depends 
upon: The pressure; the temperature; the state of moisture. 

Gases are measured in their condition at the time at which 
the measurement is made; that is, at the atmospheric pressure 
as indicated by the barometer and at the temperature as indi- 
cated by the thermometer, and, as the confining liquid is gen- 
erally water, in a state of complete saturation with moisture. 

Hence it is necessary to reduce the volume of the gas, as 

' measured under known but varying conditions, to the volume 
which it would have at the normal barometric pressure of 760 
millimetres, at the normal temperature of 0° C., and inthe dry 
state. 

According to Boyle’s law, the volume of a gas varies in- 
versely as to the pressure to which it is subjected. If 

V, = the volume at the normal pressure sought; 

V = the volume at the barometric pressure B; 

£& = the state of the barometer at the time of the observa- 

tion,—-we have 


—— 
= - 

- 

- 


STOICHIOMETRY. 333 


The expansion by heat of a gas is s1, of its volume at 0° 
for each degree C. 
Hence, if a gas measures 273 cc. at o° C., it will measure 
273-7 cc. at 27°C. If 
V, = the volume of the gas at the normal temperature; 
V = the volume of the gas at the temperature 7; 
¢ = the temperature at the time of observation,—we have 


7 2 p23 
0 Nema NE we ae ee ee 
273 +2 


If a gas is saturated with moisture by contact with water, 
it always takes up the same quantity of water under the same 
conditions. This water is itself transformed into the gaseous 
state, and exerts a certain pressure called the tension of aqueous 
vapor. ‘This tension of the aqueous vapor increases as the tem- 
perature increases. This tension has been determined experi- 
mentally (see Tables), and must be deducted from the observed 


barometric pressure in each determination. 


If B — f =the corrected barometric pressure, we have the 
following formula, which embraces all corrections: 


_ VX 273x(B—S) 
13s eres ctu cer a eae erate a 1) 


The reduction of the volume of a gas to the normal state 
may be omitted in cases where only approximate results are 
required, and also in determinations which are made rapidly, 
as material changes of pressure and temperature are not to be 
expected. es: 

To reduce the volume of a gas from the normal state to 
that which it would occupy at a different pressure and tem- 
perature, and in a state of complete saturation with moisture, 
we have the equation 


la V(273+2)760 ; 
273(5 =f) 


EXAMPLE No. 24. A gas measured over water occupied a 
volume of 100 cc., the barometric pressure being 730 mm. and 


pCa agra ial 163) 


334 A MANUAL OF PRACTICAL ASSAVING. 


the temperature being 25° C. What will be its volume at 76a 
mm. and o° C.? 
Substituting in formula A, we have 


100 X 273 X (730 — 23-58) _ 
CRE ARY SAGs = Ohl pace 


EXAMPLE No. 25. The volume of a dry gas at 760 mm. 
pressure and o° C. was 100 cc. What volume would it occupy 
if saturated with moisture at a temperature of 40° C. and 740 
mm. barometric pressure? 

Substituting in formula B, we have 


100(273 + 40)760 
273(740 — 55) 





= 127.2 CC. 


Calculation of Percentage by Weight from the Volume.— 
Having measured the volume of the gas and reduced this 
volume to the normal state (Examples No. 24 and No, 25), its 
percentage by weight may be obtained by means of Table IV, 
showing the absolute weight of gases (Tables). 

EXAMPLE No. 26. What is the percentage by weight of 
nitrogen in a substance of which 1.0 gm. yielded 4o cc. of dry 
nitrogen gas at 0° C. and 760 mm. barometer? 

By Table IV we see that 1000 cc. of dry nitrogen at 0° C. 
and 760 mm. weighs 1.2562 gms.; hence 


1000 : 1.256237 40: 4; 4 /==0.0502hmenies: 
and 
1.0 3: 0.05025 !; l00¢ 4s 92 = 15 Ogeaene 


EXAMPLE No. 27. One gramme of a substance upon 
analysis yielded 150 cc. of carbonic-acid gas, the gas being 
measured at 22° C. and 750 mm. barometer. What is the per- 
centage of carbon in the substance? 

Substituting in equation A, we have 


_ 150(273 X 730.3) 


*  (@73 + 22)760% 1 | ya 


STOICHIOMETRY. 335 


By Table IV we find that 1000 cc. of dry CO, in the normai 
state weighs 1.9663 gms.; hence 


Moen O03 3: .134.05 2243) 4 =.0.2030 om. 

and 
MOe0.20307- 100% 45-72 = 20.30% CO; 

and 


Beret 26-2020: 30t 2 + Y= 7. 15%. C, 


When the percentages of the different gases are deter. 
mined by volume (see Part III, Chapter XI), the calculation 
will be as follows, no corrections for barometric pressure, tem- 
perature, etc., being necessary: 


Analysis of Coal Gas. 


Volume of Gas employed, 100 cc. 


A. Estimation of the Absorbable Constituents. 


After absorption with caustic potash.........., 98.6 cc. 
Wecredse Ot VOLUME. .a.5 cece eee 1.4 ‘* = 1.4 volume per cent 
After absorption by bromine water and removal of carbon dioxide. 
of the bromine vapor by caustic potash...... 94.8 °° 
Ne AG cela os led 6 einwan ss photetann 0 08 =. Ou Del Cent Mell ys 
lene, propylene, 
After absorption by fuming nitric acid and re- butylene. 
moval of the nitrous fumes by caustic potash. 93.8 ‘‘ 
MAR arate oie sald lie se + Soe asicke'vinle, Dain 1.0 ‘‘ = 1.0 per cent benzine 
vapor. 
After absorption by potassium pyrogallate..... O13; Rane 
eRe aS Se ay Sana ohy, b.eales x ole Wales 0.3 ‘* = 0.3 percent oxygen, 
After absorption by cuprous chloride.......... ely Be ot 
Decrease: sic... . hes sOsrtin of sate iotaigian Meet tie 6.5 ‘‘ = 6.5 per cent carbon 
monoxide. 


Non-absorbable remainder.......+..- Hiecstee saree ye oe 


330 MANUAL OF PRACTICAL ASSAYING. 


B. Estimation of the Hydrogen and Methane. 


A portion of the unabsorbable remainder is now drawn off 
into a eudiometer, mixed with oxygen, and exploded. 


Volume of unabsorbable remainder drawn off into 
eudiometer (corresponding to 35 cc. of the orig- 


PN ALIDAG) iow athe vaste Son 5 ose sk rein eee ing cei neee 30.5 CC. 
Volume before explosion (57 cc. of oxygen added).. 87.5 ‘ 
Volume after explosion.......... bi uParbieraratethiaisttateies 50.0 *f 
Decrease (H2O)....... saleeek cepreih cerns Sok ote eee 37 ee 
Gorresponding to‘hydrogen., 2. .20,. «2. aseuom econ eee meee 
ADR VON waveva'e 1506 his amie 1k 14) = 99 idle ARNE Low alle oa ens Sched 12.59 
Volume after absorption of carbon dioxide with 

potassic hydrate... seep sas ecu enieeae ae 43,.0°mee 
Decrease (CO a) io. ahs, qs ool wotetene tianete teres a eieaen tee 7 0ngen 
Corresponding to carbon... ...sa «ann ence sin, Sues 24900 

& *  OXYLENs a cet a vanes Heine haieees 4.66 
Oxygen added fc. sinbt= seine kee Oars sien urertai ieee 57.00 ** 
Oxygen combined as water and carbon dioxide 

(22:50 4-406). 0 ssn teem eieeeies Rist aezee HE ee 17.1052. 


Oxygen remaining after treatment..............-. 39.84 ** 
Volume of oxygen and nitrogen remaining after 


treatment... vec ss cose ek enene my tee o« 45,0000 
Nitrogen (43.00 — 30.82)..010 6;,.e6 teense meen sweets 3.16 * = 9.03% nitroger 
Carbon calculated to methane (CH,)...........+++ 11.65 ‘* = 33.28% methane 
otal Hydrogenis Ssctaw wcreleinwis' © Wisvemie otatwintede § aay ene 2500hee 
Less hydrogen calculated to methane............ 0.3255 


Fy drogen, co cccccccccccccccccscscccccene eens ces 15.68 ** = 44.80% hydrogen 


CHAPTER: III. 
THE CALCULATION OF LEAD BLAST-FURNACE CHARGES. 


THE calculation of a lead blast-furnace charge is a more 
or less complex problem, owing to the many different points 
which have to be taken into consideration. Consideration 
must be given to the following: 

First. The charge must be calculated so as to producea 
slag which will be good from both a metallurgical and an 
economic standpoint. A good metallurgical slag is one which 
is fusible, is adapted to the ores to be treated, should keep 
the furnace in good condition, should allow of a good separa- 
tion of matte and speisse from the slag, and should be low in 
both lead and silver. An:-economic slag is one which will fulfil 
the above conditions and at the same time allow an economic 
mixture of the ores to be treated and require a minimum 
amount of costly flux. For example, at the present smelting 
centres of the West the majority of the ores received are dry 
silicious ores, and these are the ores in which there is the 
largest margin of profit. Lead, iron, and lime are necessary 
fluxes which have to be added to the charge to produce the 
proper amount of bullion and the proper slag, and these fluxes 
are more or less costly, as they have to be purchased at a price 
which allows little or nothing for smelting, and for every pound 
of flux added to the charge one pound less of ore, in which 
there is a profit, can be added. The amount of time, fuel, 
labor, etc., expended in smelting a pound of flux is the same 
as that expended in smelting a pound of ore. The following 
table gives the different type slags which are good metallurgi- 
cal slags. 7 
‘ 337 


338 A MANUAL OF PRACTICAL ASSAYING. 


Slag A is a good slag, which has been used in Utah and 
elsewhere for several years. It is especially adapted to ores 
carrying considerable alumina. This slag cannot be success- 
fully made with impure ores having a high percentage of zinc. 

Slag B is a favorite slag with Utah smelters, and is one of 
the best slags which we have, being more fusible and driving 
faster than A. This slag is not adapted to ores containing 
high percentages of zinc. 


TABLE OF TYPE SLAGs: 


: SiOg. FeO. CaO. ZnO, 
Notation. Per Cent. Per Cent. Per Cent. Pér Cent, 





Aizen. tse 35 28 28.0) Sea eaee eee 
1S BARN seaee 34 34 ZA = neha te atelane 
Ce Bee 34 34 17 7 

Daca 30 40 20 27a 
1G ee Saas 30 48 12 > ie eee 
Fy eke 28 to 30 54 MEME [i arak Bore Sn 





Slag C is a favorite type with Colorado smelters, as it runs 
well with high zinc charges, which is generally the rule in 
Colorado. As the percent of zinc on the charge decreases the 
per cent of lime is raised, the slag more nearly approaching 
type B in composition. Types B and C really belong to the 
same general type, and are very similar in many of their physi- 
cal properties. 

Type D is a most excellent slag, generally known as “the 
half slag.” This slag was formerly much used by Colorado 
and Utah smelters, but owing to the scarcity of iron in the 
ores of late years it is seldom used now. 

Slag E is what is generally known as “the quarter slag,” 
and was much used in the early days of smelting in Utah and 
Leadville when the ores were generally oxidized ores carrying 
a high per cent of ferric oxide. It isa most excellent slag, 
and answers all metallurgical purposes, but can only be run in 
exceptional cases owing’to the prevailing scarcity of iron in the 
ores. 

Slag F is not as good a slag as any of the foregoing, and is 


: 
¥ 
5 
; 





CALCULATION OF LEAD BLAST-FURNACE CHARGES. 339 


only to be recommended in certain rare and isolated places 
where there is a large excess of iron in the ores, and silicious 
ores are not available. 

In all of the above types the sum of the SiO,, FeO, and 
CaO is considered as making about go per cent of the slag 
constituents. This will be found to be the case except when 
the ores contain much ZnO and Al,O,, MnO being considered 
as FeO and MgO and BaO as CaO. Up tocertain limits MnO 
will satisfactorily replace FeO, and the same may be said of 
MgO and BaO as regards CaO. Too much MnO (above 7 
per cent or 8 per cent) seems to have a tendency to carry silver 
into the slag and too much MgO or BaO (above 4 per cent or 
5 per cent in high lime slags) has a tendency to render the 
slags more infusible and pasty, and is liable to cause trouble 
in the furnace. 

Second. The charges must be calculaed with regard to the 
ore supply on hand, and what may be expected from the daily 
receipts of ore; that is, the products of the roasting and fusing 
furnaces, and the raw smelting ore coming to the works, must be 
used in about the proportions in which they exist, so as to not 
have a surplus of certain ores or products on hand. Hence the 
metallurgist must keep posted as to the condition of the ore 
market, and the ore-buyer must keep posted as to the require- 
ments of the metallurgist. | 

Third. The charge must not only be so calculated that we 
will have a sufficient amount of lead on the charge, but also so 
that the bullion will be of the proper grade. In the early days 
of smelting in this country a 20-per-cent lead-charge was not 
unusual, while at the present time a I2-per-cent charge may 
be stated as the average charge. As low as a 6-per-cent lead 
charge has been successfully smelted, but for good work, on 
fairly high-grade bullion, 10 per cent may be considered as the 
limit. A charge of over I2 per cent is rarely permissible in the 
Western smelting centres on account of the scarcity of lead and 
its high cost asa flux. The grade of the bullion must be taken 
into account, as, for example, some refiners will not pay for gold 
in the bullion if it is less than I ounce per ton, and gold ores 


340 A MANUAL OF PRACTICAL ASSAYING. 


are frequently scarce. The smelters generally pay for 95 per 
cent of all the gold in ores which assay over 0.I ounce per ton. 
Also, on account of freight rates and refining charges many 
smelters are required to keep the silver contents of the bullion 


within rather narrow limits, as, for example, not below 250 nor 


above 300 ounces per ton. Account must also be taken of the 
silver and lead losses in smelting, the amount of silver and lead 
which goes into the matte, and the amount of silver and lead 
which goes into the flue-dust, in determining the amount of 
bullion which should be produced. No exact rule can be given 
for determining these points, as they will differ according to the 
individual practice of the works, and can only be settled by the 
actual results at any particular works. 

Fourth. In addition to the slag and bullion-making ele- 
ments present in the charge, we have such elements as sulphur 
and arsenic, part of which elements go to make matte and 
speisse (a small amount also passing into the bullion), and part 
are volatilized in the furnace. The composition of pure iron 
matte is FeS, but as the furnace-matte invariably contains Cu, 
Ag, Pb, Zn, and other constituents of the charge, its composi- 
tion is variable. The composition of speisse varies from Fe,As. 
to Fe,As when pure; but it almost always contains Cu, Co, Ni, 
etc. Hence no exact rule can be given for the allowance of 
iron to be made for the sulphur and arsenic on the charge. 
Just what the composition of the matte and speisse will be, and 
what the loss of sulphur and arsenic will be, will depend on the 
character of the ores under treatment and the working of the 
furnace. These points can only be determined by actual prac- 
tice in each individual case. A rule which answers very well 
(until a more reliable one can be formed based upon the actual 
results from the working of the furnace) is to allow sufficient 
iron to convert one half of the sulphur on the charge into FeS. 
For arsenic allow sufficient iron to convert all the arsenic on 
the charge into Fe,As. As the smelting of sulphide and 
arsenical ores is now usually preceded by roasting, the amount 
of S or As on the charge will not be very large. 

In the case of ores containing copper, which is almost always 





CALCULATION OF LEAD BLAST-FURNACE CHARGES. 34I 


present, the charge must contain sufficient sulphur to convert 
all of the copper into matte, as otherwise there will be trouble 
with the lead-well and hearth of the furnace. 

Fifth. The size of the charge and the amount of fuel must 
be taken into consideration. The size of the charge will de- 
pend, to a great extent, upon the size of the furnace. A usual 
charge is from 700 to 1000 pounds—the latter being a very 
convenient ore-and-flux charge for a modern, large-sized blast- 
furnace. In making up a charge, the total weight will fre- 
quently run under or over the weight which is desirable, but 
as the question is simply one of proportion the desired total 
weight can be obtained by increasing or reducing the weight 
of each ore, the limestone, etc., by 0.1, 0.2, or whatever pro- 
portion will give the desired weight. The weight of fuel to be 
used will depend upon the character of the charge, the fusibil- 
ity of the slag, the altitude of the place at which the smelter is 
situated, the character of the coke and charcoal, and the di- 
mensions of the furnace. The fuel is usually spoken of as such 
a per cent of fuel, which per cent may vary from 12 to 24. 
This per cent is such a per cent of the total weight of the ore 
and flux exclusive of whatever slag, from previous operations, 
may be on the charge, unless the amount of slag is large, when 
ssome fuel must be allowed for it. The amount of sulphur on 
the charge will affect the fuel-charge, as some of the sulphur 
will act as a fuel. The amount of lead will also affect the 
amount of fuel necessary, as high lead-charges will require con- 
siderably less fuel than low lead-charges. As an example of 
the effect of altitude, at Leadville (10,000 feet above sea-level) 
from 20 to 22 per cent of fuel is necessary, whilst at Denver 
(5000 feet above sea-level) 15 to 17 per cent is the usual charge, 
the ores and fuels in both cases being practically the same. 
The character of the fuel will make a considerable difference, 
as, if the coke is poor and friable, there will be considerable 
waste in handling, and in the furnace, for which allowance must 
be made. The amount of ash which the fuel contains and its 
composition will also have to be taken into consideration. In 
the winter, when the coke is apt to be damp from snow and 


342 A MANUAL OF PRACTICAL ASSAYING. 


rain, allowance must be made for the moisture by allowing an 
increased weight of coke. 

The above percentages of fuel are based upon a good, hard, 
dry coke, containing about Io per cent of ash, which contains 
from 55 to 65 percent of silica. High lime-slags, and especially 
those which contain much baryta, will require a slight increase 
in the per cent of fuel. 

From the above it will be seen that to calculate a charge 
the first step is to assume the different ores and their amounts 
which we will have on the charge, due consideration being given 
to the above points when making this assumption. The second 
step is to find the total amounts of silica, ferrous oxide, lime, 
etc., in the weights of ore as assumed, which is accomplished by 
multiplying the weight of each ore by its per cent of silica, 
ferrous oxide, etc., and taking the sum of the different weights; 
a convenient way being to tabulate the results as illustrated in 
the examples. 

If we assume the following notations for the totals and per- 
centages: 4A = pounds of SiO, in the ores (total); B = pounds 
of FeO in the ores (total); C = pounds of CaO in the ores 
(total); a= per cent of SiO, which the iron ore (iron-fiux to 
be added) contains; ¢ = per cent of SiO, which the limestone 
(lime-flux to be added) contains; f= per cent of FeO in the 
iron ore; /= per cent of CaO in the limestone ; Y = pounds 
of iron-ore required, and Y = pounds of limestone required, 
we have for slag A 


(A + Xd+ Ve) =BLXF 
or 


B(4 + Xd + Vy) =BIS. ... (i) 


and 


C+ Vi= BAX a 


CALCULATION OF LEAD BLAST-FURNACE CHARGES. 343 


Solving equation (2) with respect to Y, we have 


ie 59 ean 
ya tsa, (AN 


Substituting this value of Y in equation (1), we have 


be+ Xef — C 
a) Bt Xe. 


Sat xd 


Reducing and transposing, we have 
5SA/l — 4Xef — 4Xdl = 4Al+ 4Be — 4Co — 5 Bl, 
Solving with respect to ., we have 


| 441+ 46e— 4Ce — 5 Bl 
pene 47 mad EY 





For slag B we have 


NG Vea BR Nfs ie UG) 
24 
Bt = on G) 


Solving equation (2), with respect to Y, we have 


12B+ 12Xf—17C 


A Lf 


ie? ek eins (8) 


Substituting this value for Y in equation (1), seducing and 
solving, we have 


17Al4+ 12Be — 17Ce— 1781 


“ia 17fl — 12ef — 17al ons Va) 


344 A MANUAL OF PRACTICAL ASSAYING. 


In like manner we obtain for slag C 


2Al+ Be — 2Bl — 2Ce 





4 fl fal) 
BX f see 
ie a1 Hs Ly Ofaee : e @e@ e ov {C) 


and in like manner for slag D, 


4Al+ 2Be — 3B1— 4Ce 


X= yo ee Om 


37¢ — 2ef — 4al 
yao 


and in like manner for slag E, 
xy! 8Al+ 2Be — 5Bl— 8Ce 
ah tfl — 2fe — 8al 


BAXf—4C 
7; cau e 48 | ©. 0). eee (E’) 


rere i 


Y 


and in like manner for slag F, 


gAl+ Be— 5Bl—oCe 


X= og ee 
BAX EOG 
gr aa . a ee 


In like manner general equations may be deduced for any 
type of slag which it is desired to make. 

Having obtained the above formule it is only necessary to 
substitute for A, B, C,d, etc., their proper equivalents in the 
first formula to obtain X. Having obtained X, substitute its 


value, together with the proper equivalents of B, f, C,and Zin - 


the second formula to obtain Y. 
The calculation of a charge is best illustrated by the follow- 
ing examples: 


— ad 


. 


CALCULATION OF LEAD BLAST-FURNACE CHARGES. 345 


EXAMPLE No.1. We have 50 tons per day of fused ore, 80 


tons per day of roasted ore and matte, a bed of 2000 tons of ore 


which it is desirable to smelt in about two weeks, and a supply 


‘of silicious silver ore which it is desirable to smelt as rapidly as 


possib:e. In addition we have a regular supply of iron ore, 


limestone, and coke. The analyses of the ores are as follows: 





Per Ct./Per Ct.}Per Ct.|Per Ct.|Per Ct./Per Ct. et ote Per Ct; Ered Nahe 


E@SeE 0.) Ca0.|-Al,0y.| Za, | Cu, Ste carecal age 
Fused..... 30 30 8 : 15 3 50.0|I.00 
Roasted 10 30 8 6 20 5 52-5|0.50 
(no ea 28 21 4 4 5 2I 2 55.0/0.30 
SILVel go 6 : : LOO O}.(2 
Iron Ore 10 75 a's ene Ma Ya aa | rai coe Seva tate! Peet reat cat He cree RN Ve oe 
Limestone 5 ee, 50 Serra Paaincalneieca ws tara ti ee Mlle a eet Pucca ee he 
MORE. oe! acs 5 case 2 CS hl CROP cee RPA | arene nesaoahat Fen 





* Ash = 1o per cent. 


Suppose we assume that we will smelt the ores in the same 
proportions as we have them on hand and smelt 50 pounds of 
silicious silver ore per charge, and use 150 pounds of coke for 
a 1000 charge... A convenient method is to tabulate the results 
as follows : 






































Ore icbs.per) Lbs, | Lbs. | Lbs.| Lbs. | Lbs:| Lbs.) Lbs.| Lbs.| Oz. Oz. 

, Charge.| SiO,. |. FeO. |CaO.| Al,O3 | Zn. | Cu. | Pb.| S. Ag. Au. 
Pused......:}|' 100 | 30 AON woe tee MeO eet St eS hen ee RO O1 G8 
Roasted....} 160 16 AOU task yt wi eee ool GeO tsa Soh es 20) OL0d 
ISeseise se). G00 | (84 63 pie al Tie fate 003 Ouleite 12617 0.048 
Silver 50 45 3 MT dS redaveipaie what: Meee dares Wa) ee oe 
SSOKG. 50%. vs 150 re Bx bie Var ore tee ok malls ce'at eaves 

Total...) 760 | 182.5] 144 15 136.5 13579).0.0) FIO) 17°) -17,.451°0.895 





Calculating one half of the sulphur to Cu,S and FeS, we 
have: 126.8 (mol. wt. of 2Cu) : 158.8 (mol. wt. of Cu,S) ::9.6 
Missin ibs. of Cu,S);.4 == 12. 

Hence 12 — 9.6 = 2.4 lbs. of S which the Cu present will 
take up. Now 4 — 2.4 = 6.1 lbs. 5 to be taken up by Fe. 

Hence 32 (at. wt. S) : 88 (mol. wt. FeS):: 6.1 : x (Ibs. of FeS 


340 A MANUAL OF PRACTICAL ASSA YING. 


which will be produced by excess of S); + =16.7. Hence 
16.7 — 6.1 = 10.6 lbs. of Fe necessary to take up excess of S. 
The following gives the amount of FeO to be deducted from 
the total pounds of FeO on the charge on account of sulphur, 
10.6 X # = 13.6, and 144.0 — 13.6 = 130.4 Ibs. vols heQwawans 
able. | 

From an inspection of the above totals slag ““C” appears to 
be an economical and good slag to make. Substituting in 
equations (C) and (C’) we have 


_( X 182.5 X .5)-+(130.4 X .05) — (2 X 130.4 X .5) — (2 X 15 X .05) 
(2 X .75 X 5) — C75 X -05) — (2 X.1 KB) 





as = 93:25 


_ 130.4 ++ (93-2 X75) — (2 XK TS) 


VY soiey hy] 2 
2X Gs ed 





As some of the zinc is volatilized, some passes into the | 
bullion and matte, and some goes into the wall accretions of the 
furnace, it is necessary to assume what amount will pass into 
the slag. If we assume that 80 per cent of the zinc passes into. 
the slag as ZnO, we will have 35.6 pounds of zinc oxide avail- 
able as slag-making material. In order to calculate the per- 
centage composition of the slag, which will result from the 
above charge, it will be necessary to calculate the: pounds of 
SiO,, FeO, CaO, etc., in the weights of iron ore and limestone 
on the charge as determined above, and add these weights to. 
the above weights of available SiO,, FeO, CaO, ZnO, and 
Al,O, to obtain the total weight of slag-making material on the 
charge. Making this calculation, we have 200.3 (pounds. 
SiO,) + 200.3 (pounds FeO)-++ 100 (pounds CaO) + 35.6 (pounds. 
ZnO) + 16.5 (pounds Al,O,) = 552.7. As these elements will 
not make up the total composition of the slag, it always carry- 
ing S, Pb, etc., it will be necessary to assume what proportion 
of the slag it will make up. If we assume that these elements 
will make 97 per cent (an assumption which will usually be very 
near the actual results) we will have 


«pig RO023 Ee Ova 
epi O}ice= wae 35.17 per cent, 


CALCULATION OF LEAD BLAST-FURNACE CHARGES. 347 


200.3807 


he) = peers ae eet ohel7 per Cent, 
Calle — es. emuli7 oh 5 Percent, 
‘6 
J ON oe 0.24, percent, 
Al,O Ls eine er cent 
Desa = 552-7 ang 9P ’ 


which shows the calculation to be nearly correct for the type 
of slag chosen. The amount of lead on the charge is usually 
spoken of as so many per cent, referring to the total ore and 
flux charge. The following is the calculation of the lead on 
the above charge : 


110 (pounds of lead) X 100 __ 6 
873.5 (pounds of ore and flux) — SPA AS LOS 


In order to arrive at the amount of bullion and matte which 
should be produced and its assay value, it would be necessary- 
to assume the following: 

First. The amount of the charge which will pass into the 
flue-dust. This will depend upon the amount of fine material 
on the charge, the pressure of the blast, the height of the 
furnace, and the condition and working of the furnace. 

Second. The losses in lead, silver, and gold in smelting (by 
volatilization and in the slag). These will depend upon the 
character of the ores and composition of the slag and the work- 
ing of the furnace. 

Third. The amount of lead, silver, and gold which will pass 
into the matte. These will depend upon the character of the 
slag, the per cent and character of the fuel, and the working of 
the furnace. 

All of these are variable, and will not only vary at different 
works, but will vary from time to time at any works, owing to 
the changes in the ores, the working of the furnaces, etc. 


oe 
he % : 


348 A MANUAL OF PRACTICAL ASSAYING, 


After a works has been in operation some time, reasonably 
close constants may be deduced for these vane from the 
actual results obtained in smelting. 

In the above example, suppose we assume that 2 per cent 
of the charge will pass into the flue-dust ; that the silver loss 
in smelting is 3 per cent; that the lead loss in smelting is 8 per 
cent; that the gold loss in smelting is nothing (it is usually 
unnecessary to make any allowance for loss in gold, as a works 
will usually produce more gold than is purchased, owing to the 
fact that many of the ores contain small quantities of gold 
which are not taken into account, and other causes); that the 
matte will carry about 10 per cent of lead, and that the lead 
passing into the matte will carry with it the same proportion 
of silver and gold as the lead in the bullion contains. Then, 
if the Cu,S, FeS, and Pb make up go per cent of the matte, 
we will have 

110 — g (loss in smelting) = 1o1 pounds of lead. 

IOI — 2 (amount passing into the flue-dust) = 99 pounds of 
lead. 

17.45 — 0.5235 (loss in smelting) = 16.9265 ounces of silver. 

16.9265 — 0.3385 (amount passing into the flue-dust) = 
16.588 ounces of silver; and 0.135 — 0.0027 = 0.1323 ounces 
of gold available for matte and bullion. 

The composition of the matte will be Cu,S, 12 pounds; FeS, 
16.7 pounds; Pb, 3.6 pounds. Balance (10 per cent), 3.6 
pounds. Total = 35.9 pounds. 


6. 6 
SERS AS = 0.6032 ounce Ag in matte; 
99 
O:022255012.0 ; 
iene = 0.00481 ounce Au in matte. 


The assay value of the matte in ounces per ton of 2000 
pounds will be 


OSES ROE on Ween 0.00481 X 2000 


cae 35.9 0.27/02. AMG 


CALCULATION OF LEAD BLAST-FURNACE CHARGES. 349 


The following calculation gives the amount of bullion which 
should be produced and its assay value: 


16.588 — 0.6032 = 15.9848 ounces Ag in bullion, 
and 
0.1323 — 0.00481 = 0.12749 ounces Au in bullion, 


15.98 + 0.127 
14.58 





(99.0 — 3.6) + = 96.51 lbs. of bullion 
which should be produced. The assay value in ounces per ton 
of 2000 pounds will be 


15.9848 X 2000 _ 
re Bali, O2.0i2, 


and 
0.12749 X 2000 


GEE ee OAROZ eV Us 


The total pounds of ore and flux on the charge is 873.5. If 
we desire a 1000-pound charge, this weight is too small by 
about 15 per cent. Increasing the weight of each ore, the iron 
ore and limestone by 15 per cent, we have, for the chargé, fused 
ore, II15 pounds; roasted ore, 184 pounds; bed, 345 pounds; 
silver-ore, 62.5 pounds; iron ore, 107.2 pounds, and limestone, 
194.9 pounds. 

As it is usual to set the furnace scales only to every 5 
pounds difference in weight, the charge would be— 

Pounds. 
Pe ULOLO Maret 56>) 0) komm whe tom LS 
Peres CULOTC 8 tot os Leet cee ot aee EYO5 
OR ge eel aerials!) 6 ies 6 a eee era AS 
Pee ROL CA ae hele” a in ihe er ctetel EOS 
McCue. fue. lL oitre the aie! caries aL LO 
BICSCONG is lala fc, oe tte tte mee ent OS 


Cokeii5°per cent of 1015), <>» 4150 


350 A MANUAL OF PRACTICAL ASSA YING, 


As the analyses are made on the dry ore, allowance must 
be made in making up the charge for the moisture which the 
ores. contain. In the above example the only ores liable to 
contain sufficient moisture to require allowance for it are the 
bed and the iron ore. Allowance would be made in the case 
of these two ores by adding such a number of pounds as the 
moisture determinations, made from time to time, show to be 
necessary. 

EXAMPLE NO. 2. Suppose we have the following ores: 
































Ore Tonson|Pr. Ct.|Pr. Ct.|Pr. Ct. |Pr. Ct.|Pr. Ct.|Pr. Ct. Pr, Ct.|Pr.Ct.| Oz- | O2- 

: Hand. | SiQg. | FeO. | CaO. |Al,O;| ZnO. | Pb. Ss Cu, [PS *s(P eer. 

A Aathe 

Nose wiles 600 | 25.0] 20.9] 5.0] 5.0 | 6.0] 20.0] 3.0 30.0) 0.05 
lbh eee 200. |/;QO7O) (7 20) eee cas Ce} atk inie | kins BO ee ..|I00.0) 0.50 
ORE AR eos 200 | 15.0] 30.0].....| 3.0 | 10.0] 15-0)/6,0)) 570 | eon mauea 
Doane AoE 20:0]. Ab20) cued The) Gee eee S .Ohishye 
Limestone.. a GB Olin ees oF 0) PS I PPS ee re 
Iron ore... - 5.0] BOLO. . see fcwe oe |'s aie a ie cereal eines ee sc afean 
MOORE site sls - OOS sa ua te AsO | uieie ¢eilla isha 0) oA pueele oral ee eee ee 














If we smelt the ores in the proportions in which we have 
them on hand and use ore D for iron-flux, we have 


Ore, |Lbs.per| Lbs. | Lbs. | Lbs. | Lbs. | Lbs. | Lbs. | Lbs. | Lbs. | Oz. | Oz. 























Charge.| SiOs. | FeO. | CaO. |Al,O,|ZnO.| S. | Cu. | Pb. | Ag. | Au. 
Aah ie g00. 75 6229) 15 15 18 O 1 cea 60 | 4.50/0.00750 
ES heats 100 go ys) PI UI rei ar he 5.00/0.62500 
Ce Shrler Loo I5 SOLO hate 3 10 6 5 15 | 1.00/0.02500 
Coke 150 Oth sae ect eee Ol Fs el alee Bert at oi | ts eh abe apereree 

Lotal) css 18g | 10026) (15 24 28 15 5 975 110.5 |0.05750 


Calculating one half the sulphur to Cu,S and FeS, we have 
86.2 pounds available FeO. Assuming that 80 per cent of the 
ZnO passes into the slag and adding this to the CaO, we have 
for available combined CaO and ZnO 37.4 pounds. Substitut- 
ing in equations (B) and (B’), we have 
xa UX 189 X0.5)-+(12 X 86.2 X 0.05) —(17 X 37.4 X0.05)—(17 X 86. 2X0 5) 
| (17 X0.45 X0.5) —(12 K0.05 X0.45)—(17 X0.2 X0.5) 


: \ 8 : =— . 
y= (2 X 86.2) + (12% 460.7 60:45) 7S 
17 X 0.5 





=480.7 


CALCULATION OF LEAD BLAST-FURNACE CHARGES. 351 


From the above we have 10.8 per cent of lead on the 
charge, and allowing for a 10-per-cent lead loss and a 4-per- 
cent silver loss in smelting, the bullion should assay about 
182.7 ounces of silver and 0.88 ounce of gold per ton of 2000 
pounds. 

Taking the sum of the pounds of ore and limestone on the 
charge, we have a total of 1333 pounds, which is about 25 per 
cent too much if we wish a 1000-pound charge. 

Reducing the weights by 25 per cent, we have, for the 
corrected charge, 

Pounds. 


eee PE ie) ole e's 228 
Peta e/a gies Se vets 8 gn 6 75 
ee es Phase wre ge tis. 4 75 
ieee i ihc wan be, ols: fs =» 1s. 300 
CEC a esn oe oie ee) xe 205 


—___ 


1000 
emi i tc st. ee) sv TSO 


EXAMPLE NO. 3. Suppose we have assumed the number of 
pounds of several ores which we will smelt on a charge, and 
have figured out the total pounds of SiO,, FeO, etc. The 
totals are as follows: 


subs; » Lbs, Lbs. PpseesUbs.)t’ Lbsot ‘Lbs... Lbs: Oz. Oz. 
SiO,. FeO. ote Als. 2200. Cu: Pb. S: Ag. Au. 


ee Pees 30/55 12, 27.5 LI - 17.5 19.25 0.1075 


Assuming that one half of the S passes into the matte as 
FeS and Cu,S, we have 161.3 pounds of FeO available for slag. 
We have, for fluxing, iron ore containing SiO, 5 per cent, FeO 
80 per cent; and limestone containing SiO, 5 per cent, and 
CaO 50 per cent. Slags A, B, or D are all good slags for the 
above charge. If we prefer to run slag A, we have by substi- 
tution in equations (A) and (A’) 

_ (4X 211 X0.5)+(4 X 161.3 X0.05)—(4 X 54.5 X0.05)—(5 X 161.3 XO.5)} 
< (5 X0.8 X0.5)—(4 X0.05 X0.8)—(4 X0.05 X0.5) 


ie 161.3 +(17.5 X 0.8) — 54.5 
0.5 


xX = 17.5, 


Y = 241.6, 


352 A MANUAL OF PRACTICAL ASSA YING, 


Hence we would require 17.5 pounds of iron ore and 241.6 
pounds of limestone to flux the charge. 

EXAMPLE No. 4. We have on a charge, before fluxing, a 
total of available pounds as follows: SiO, 200, FeO 160, and 
CaO 40. 

Iron ore containing SiO, 5 per cent and FeO 75 per cent 
costs $6 per ton. Limestone containing SiO, 5 per cent and 
CaO 50 per cent costs $1.50 per ton. It requires 15 per cent 
of coke to smelt the charge, and the coke costs $10 per ton 
of 2000 lbs. 

What type of slag would be the most economical ? 

Substituting in equations (A), (A’), (B), (B’), and (D), (D’),. 
we obtain the following: 

Slag A will require 15 pounds of iron ore and 260 pounds. 
of limestone. Hence the flux will cost $0.235 per charge, and. 
the fuel necessary to smelt the flux will cost $o0.206. Total 
cost, $0.44. 

Slag B will require 75 pounds of iron ore and 260 pounds. 
of limestone. Hence the flux will cost $0.3862 per charge, and 
the fuel necessary to smelt the flux will cost $0.225. Total 
cost $0.61. 

Slag D will require 175 pounds of iron ore and 52 pounds 
of limestone. Hence the cost of flux will be $0.559 per charge, 
and the fuel necessary to smelt the flux will cost $0.1688. Total 
cost, $0.73. 

With labor and general expense at $1.25 per charge, slag 
B would have to drive 13 per cent faster than slag A, and slag 
D would have to drive 9.6 per cent faster than slag B, and 23 
per cent faster than slag A to be as economical, other condi- 
tions being equal. | 


aS 


TABLES. 





‘DABLE: I: 
WEIGHTS AND MEASURES. 


MEASURES OF CAPACITY. 
Grains of Water Cubic 


Gals. QOts. Pts. Fl. Oz. Fl. Dr, at bao" Ceatimeces. 
eee 128 i 1,024. | =) 58,318.00 = | 3;'785.200 
r=-2>= 32 = ~— 256 = 14,579.50 = 946.300 
1) Eee oe Lea £29 5 Ae TS 28OL76e = 473.150 
tas ss 455.61 = 29.570 
jeg me 56.95 = 3.690 
1 English imperial gallon = 277.274 cu. in. = 70,000.00 = 4,543.000 
I ‘¢ wine or Win- 
coester gal. | =" 23r:000  -** E750. 316,00) 4 ==) 13,758,200 
I ‘¢ corn gallon =4°208:000., * ** ==" ).67, 501.00 ) ==74,402.900 
I #4 vale a BSE eo2 COO. = ** mt, £94.40) “= 94,019) 200 
I Cio tt. == 284. 15 60, 
; Che 1. == 16,38 “ 
O.H0TO27) = = rey 


LINEAR MEASURES. 


Py.) = 3it, = 361in. = 0.91438 metre. 
Tet hea eS. Ie ae BOA BOY ee 54 
Tat, et O10 2540) att 
B.3 700. 10.9,7>27- 5,00000 fs 
Troy WEIGHT. ' 
1lb. = 1202. = 240dwt. = 5.760grs. = 373.2419 grammes. 
Leeeieas= = 207%" = A8OO NS Sel Ose 
I 66 = 24 «sc = 1.5552 cs 
Ti) oe tess 0.0648 . 


AVOIRDUPOIS WEIGHT, 


Igrosston = 20cwt. = 2,240lbs. = _ 1,016.00 kilogrammes. 
I 6é = 112 6é —_ 50.80 6é 
Z Grs. Troy. Grammes, 
Tel eee 10S. | 7,000.00 == 945 3,5020 
I = 437.50 = 28.3495. 
Tnet ton “= 2,000 lbs. = 907 kilogrammes. 
I cu. ft. of water at 62° F. = 62.3550 lbs. Av, 28,315.0000 grammes. 


O.030Tvew jana = 16.3862 a 


66 “6 Le 


I cu. in. ** 
APOTHECARIES WEIGHT. 
g6 dr. = 288 scruples = 5,760 grains = 373.2419 grammes, 


1(3)= 8(3) 24 480 31.1035 |“? 

I ( 3 ) 3 60 3.8879 He! 

I (Dd) 20 1.2960 ee 

0.0022 lb. Av. = 0.03527 0z. Av. = 15.4328 = __ 1.0000 “6 
35s 


he a ae 
Cl ae ee 



































354 A MANUAL OF PRACTICAL ASSA VYING. 
TABLE GLE 
ATOMIC WEIGHTS. 
- - omic | - - 1 

Name. pen Apna Woght. Name. pit Cee Weiwhe 
Aluminium....| Al IV 2760 |i Mércury ssue ee Hg IT 200.0 
Antimony.....| Sb V 120.0 | Molybdenum..| Mo VI 96.0 
ATSEnICS.. ssn As V 74.0.1| Niekelmetias as Ni VI 59.0 
BATU chaise a Ba II 136.8 ||Nitrogen...... N Vv 14.0 
BISMULD <n sia v Bi V 270.0 HOSmilimt. tear Os IV 199.0 
BOTONA Rn. os ely itt ir.0 WOxyoen a, eee O II 16.0 
Bromine... «<5 Br if 80.0 ||Palladium.....| Pd IV | ,106.0 
Cadmium... s..'.)6 Cd i 112.0 ||Phosphorus...| P Vv 31.0 
(ceSiiti atts. 2 ae Oe I 133.0 1 Platinunis sa Pt aa 197.0 
Calenims../ancste Ca II 40.0 ||Potassium....| K I 39.1 
Carbonignasee ae IV 12.0: 1/Rhodium..2vs.) eRe IV 104.0 
Gerinmss: >. scat ee III 141.2 ||Rubidium..... Rb I 85.0 
Chionneee ae Gl I 35.5 ||Ruthenium....| Ru IV 104.0 
Chromium....| Cr VI 52:4. ||Selenium, 2.42) moe II 79.0 
Copaltiweene) Co VI 59:6 || Sulican sa ee Si IV 28.0 
. Columbium... Cb V 94.0: ||Silverc.). coutene Ag I 108.0 
Coppet.e. binG Cu II 63.1 |\Soditum. 5. .ae Na I 23.0 
Didymium....| D III 147.0 ||Strontium..... Sr II 87.5 
Erbium. ves E III 169.0 j|/>ulphur ane S iy 32.0 
BiuGrine. whack F I 19.0 ji) Tantalaume ase le. V 182.0 
AGAIN ence Ga III 69.9 ||Tellurium.....| Te II 128.0 
Glucinum..... Gl II g.2 || Thallium fi I 204.0 
56755 (a Dyreaa eae A Au III 196.2 ||Thorium...... Th IV 231.5 
Hydrogen.... H I T.O)() Lint. 22 samppete Sn IV 118.0 
Lndium.c% a, peele een III 113.4. |) Litaniumies ee Ti IV 50.0 
Loding. ics pee. I I 126.85|)Tungsten...... * W | IV-VI} 184.0 
Tron sk fete Fe VI 56.0 ||'Uranium......| U VI 240.0 
Lanthanum....| La Lil 139.0 | Vanadium....| V V 51.2 
Weads. rte eterna D II 207.071 Y {trig oae y III 60.0 
Toithiims soci Li I 7,0 \iZINC us aeetee Zn II 65.0 


Magnesium....| Mg II 24.0 \\Zirconium «eee IV 90.0 
Manganese....| Mn VI 55.0 


a | a ae 








TABLES. 5 


PARLE Pil. 
TENSION OF AQUEOUS VAPOR AT VARIOUS TEMPERATURES,* 





Temperature | Tension of the Temperature | Tension of the 
in eee Agueous Vapor in|| in ts Aqueous Vapor in 


Millimetres. Millimetres. 
re) 4.525 21 18.505 
f 4.507 > 22 19.675 
2 5.231 23 20.909 
3 5.619 24 22 211 
4 6.032 25 23.582 
5 Ornate 26 25.026 
6 6.939 27 26.547 
| 72426 28 28.148 
8 7.964 29 29.832 
9 8.525 30 31.602 
10° g.126 31 33.464 
rt 9.751 32 35.419 
12 10.421 6) 37-473 
13 II.130 34 39-630 
14 11.882 35 41.893 
15 12.677 36 44.268 
16 13.519 37 46.758 
17 14.409 38 49.368 
18 15.351 39 52.103 
1g 16.345 40 54.969 
20 17.396 








-* For a more complete table see Winkler’s ‘‘ Technical Gas Analysis.” 





* 


356 A MANUAL OF PRACTICAL ASSAYING. 


TABLE IV. 
DENSITIES AND LITRE-WEIGHTS OF GASES AND VAPORS.* 





tooo cc. of the 
Molecular Gas in the 


Name of the Gas. Rare Density. Normal State 
weighs, 
Grammes— 
Acetylentsns cha poves 4d 0 sete vinire ne CoH, 12.970 1.1621 
Ait (atmos PRELICHs eats oro'a patio e edpis areola Paeceratoie nut veel 14.422 1.2922 
MAEM IYLOUEA Ae.) seakete Ng anaes yi a toeis ameneecN H3N 8.510 0.7625 
Antimoniuretted hydrogen........... H;Sb 62.545 5.6040 
Arseniuretted hydrogen.........e0+-- H;As 38.960 3.4908 
Moist de toed ea eee ar Re 4s Gialetn eae CeHe 38.910 3.4863 
Bilylene © ois. 's v\0lesu pip eueetatpeasteine C,He. 27.940 2.5034 
Garbon, Monoxide. 1) .)..~ ss aarti CO 13.965 1.2512 
Cachon-Cioxide ns vis. s cue 2.6 eee CO. 21.945 1.9663 
Carbon disulphide.?....31> «asp eee CS. 37.905 3.4017 
Carbon oxysulphides. 13. sisi es COS 29.955 2.6839 
GhIGTIC, Jos,cer ena sice a he sic oa Cle 35.370 3.1691 
CYAN OEM esr me woe ane a rotors anette (CN)e 25.990 2.3287 
thane: ccc eee ce ets eRe ect ne CoH. 14.970 1.2413 
Ethylene. canes smn tee eae sileremersieare CH, 13.970 1.2517 
PIydrogen .24. eer eae ee ees bisohe) unio ie mlote H2 1.000 0.0896 
Hydrogen chloride... 02.00 essa 5e es ‘ HCl 18.185 1.6293 
Hydrogen cyanide. ci )e si. ciiels casts om HCN . 13.495 1.2091 
Hydrogen sulphide. ira ec ueisiae sce H2S 16.990 1.5223 
ethan estas bins scots mreceinr os alee eprcke eons CH, 7.985 0.7154 
Nitraven; sre onc: sees tl eee scenes Ne 14.020 1.2562 
Nitrogen protoxides. . stg mcnestes y= : N.O 22.000 1.9712 
INTEVIC HORUS heen er kw reine Fie eter eee NO 14.990 1.3431 
Nitroweér trioxide... cies stn ote e ce oe N2Os; 37.960 3.4012 
NitricnperOxide. ovine. ey se 6 Shain NO, 22.970 2.0581 
OXY PENS Orie us coe Oana gta tee ne rarer Oz. 15.960 1.4300 
Phosphuretted hydrogen......... sare: H;P 16.980 | 1.5214 
Propylener eon ss ae ae as ey Seances C;He | 20.955 1.8775 
Silicon tetraluorides. vs ...<n ssinetere rer SiF, 52.055 4.6641 
SUlpliur CiaRid es. suis te citer cate vite eee SO. 31.950 2.8627 
WW ALCr jacielsaiicis asin ot ee geremen meee H,0 8.980 0.8046 





* Taken from ‘‘ Technical Gas Analysis,” by Winkler and Lunge, London, 
1885. 








oe ee ee ee eee e 


“ee ee ®Peeeeee ee 





eevee eee eee ee eee 


see ew eee see eeere 


TABLES. 


TABLE V.. 


FACTORS. 





O-221 31 
0.52942 
0.78947 
0.71428 
0.48353 
0.16181 
0.41176 
0.73529 
Tryos7! 
0.68586 
0.27273 
0.38065 
0.78667 
1.25356 
0.65636 
0.70000 
1.28571 
1.38095 
0.68317 
0.86611 


MneP.O;. ae 
(NH,4)312Mo 





oo £0 ee ecereveee 


eee ree eee eeere 


ee eeesoceeseaoceee 


OsPO, 


357 





Factor. 


— —qX~Y |e — il |—cmerereo—- \ um — jj _ —_.___., 


0.27928 
0.63964 
0.36036 
2.10000 
1.29091 
0.72052 
0.38732 
0.01630 
0.03735 
0.78667 
O 30561 
0.19295 
0.52991 
O 46667 
0.13745 
0.34364 
0.10561 
0.78667 
0.60975 
0.80247 





358 4A MANUAL OF PRACTICAL ASSAYING. 


TABLE VI. 


THE QUANTITATIVE PRECIPITATION OF VARIOUS METALS 


BY ELECTROLYSIS. 





Solution. 


Au 





Nitric or sulphuric 
Double ammonium 
OXBISLE. wie apes 
Double ammonium 
sulphate... ..:5 
Double potassium 
Cyanide... +s 
Sulpho-salt........ 
In glacial phospho- 
ric acid, after 
(NH4)2COs.... 


EE 





Double ammonium 
oxalate.. 
Double ammonium 
sulphate. . 
Double potassium 
CV ANING em cele 
Sulpho-salti. an ch 
In glacial phospho- 
ric acid, after 
(NH,4)eCOs.... 


Solution. 
Nitric or sulphuric 


Bi 


ES Se ee ee ee) eee 


si i = ean +a ahs 
Cd Tl Al Fe Mn Zn Co | Ni 
_ +6 +e —e 
-f| - |+¢ +ch} — |-]= 


—. Precipitated at cathode in metallic form. 


66 6 


—/f. cé 6 
—g. 66 «6 
Je a. “ e 
a b. rT 6c 
oe, 66 66 
+ ch. $6 6s 
ae C}. «e «e 


66 


ety i ‘* after adding (NH,)2SOx. 
The corresponding potassium 
salt preferable. 
: cs ‘« after adding NasCeH,O, and 
HsC.Hs0;. 


anode as PbOg. 


ce 


é¢ 


6 


“* T1.Os. 

“© MnOsg. 

eke: incompletely. Completely from corre- 
sponding potassium salt. 


incompletely. 





* From an article by Kahn and Woodgate in J. S. Chem. Ind., vol. viii. p. 


256. 


\ RSs a 
‘ 





TABLES. 


TABI V It; 
SOLUBILITY, FUSIBILITY, ETC., OF VARIOUS METALS, 


ee ‘ 


Metal. Color. shes 
sO 2a. es yellow mal 
Platinum.. whitish to steel-gray a 
BOLLVEY s/«/<s» white 2 
RECA casas bluish si 
Mercury ... tin-white liquid 
Bismuth, ..|silver-white to reddish-wh. |brittle 
Copper.;..; red mal. 
Cadmium. tin-white ss 
Arsenic.... lead-gray brittle 
Antimony. bluish-white fa 
ERE siase eave white mal, 
Iron (cast). gray i. 
Iron (w’t). 3 ee 
BLGGly <3 5 Ke - 
Aluminum - silver-white f 
Nickel.... Pes . 
Cobalt....| steel-gray to reddish a 
Manganese grayish-white brittle 
LANG occmees bluish-white mal. 


359 








2.5-3 | I9g-20 | 1064 aqua regia 
4-4.5 | 16-21 | 1808 a 
2.5-3 |10.5-I1| 962 HNO; 
es 11.45 322 HNO; 
— 13.5 |—40*| HNO, 
2-3.5 9.7 258 HNOsz 
2.5-3 | 8.9 1050 HNO; 
I |8.6-8.7]| 320 HNOs 
4 3.9 t aqua regia 
3-3.5| 6.8 432 . 
4-5 728 228 HCl 
4-5 7 1530 HCl 
4-5 |7.6-7.8 | 1808 HCl 
6-7 |7.8-7.9 | 1808 HCl 
Qe 25 5=2, 741.700 HCl 
5-6 |8.2-8.7 | 1537 HNOs 
5-6 |8.5-8.7 | 1600 HNO; 
g-I0 | 7.1-8 | 1650 HCl 
2 6.8-7.2] II HCl 





* Volatilizes at 360° C. 


t Volatilizes at 356° C. 


360 





A MANUAL OF PRACTICAL ASSAYING. 


TABLE 
PROPERTIES OF 





J 
| Object. 
























































Ele- Obtained by or 
ment. * Precipitated with— 
K Weigh- | Precipitant PtCl,. Pre- 
ing cipitate preferably dis- 
solved in hot H,O and 
evaporated ina weighed 
vessel. 
Weigh- Precipitant PtCl,. 
ing 
Weigh- | Evaporation and gentle 
ing ignition. Volatile at 
temperatures above a 
dull red. 
Weigh- | Evaporation and _igni- 
ing tion. (NH,4).COg facili- 
tates conversion. 
Na Weigh- | Evaporation and gentle 
ing ignition. 
Weigh- Same as K,SOx,. 
ing 
Ca Weigh- riba Ae (NH,4)eC2O4 
ing or H,C,O4 in NH,0OH 
solution. 
Weigh- As above. 
ing 
Separa- | Precipitant (NH4),COs3. 
tion 
Mg Weigh- Precipitant NagHPO,. 
ing 
Separa- Precipitant Ba(OH).. 
tion 
Ba Weigh- | Precipitant H,SOx,. 
ing Should be heated before 
adding. 
Separa- | Precipitant (NH,),.COs3. 
tion 








| 


Obtained or 


Precipitated as— Conditions of Solution, 














K,PtCle Cold, alcoholic, contain- 
ing chlorides or HCl. 
Salts other than NaCl 
should be absent. Small 
amounts of Caor Mg may 
be present, but are detri- 
mental, 


KPtCle As above. 


KCl Only chlorides or salts 
converted into chlorides 
should be present. Am- 
monium salts may be 
present. 

Absence of salts forming 
non-volatile sulphates or 
containing non-volatile 
acids (as H3PO,). 


K,SO, 











Same as KCl. 


Same as K,SQO,. 











Hot, strongly ammoniacal 
and an excess of oxalate. 





CaC,0O, 


As above, 


/ 


CaC,0, 


Alkaline solution free 
from large excess of 
alkaline salts, especially 
citrates. 


CaCO 3 





Cold, containing excess of 
H,0OH +NH,Cl. Ab- 
sence of SiO, and bases 
other than alkalies. 
Alkaline and moderately 
concentrated. Free from 
ammonium salts and or- 
ganic salts. 











MgNH,PO, 


Mg(OH), 





—— 











BaSO, 





Hot, containing some free 
Absence of eee 4 
large amounts of(NH,4).S 
group and Ca salts, 


BaCO, Alkaline, containing 
NH,OH and excess of 


(NH4)gCOs3. 





* Compiled mainly from an article by Prof. E. Waller, entitled 





TABLES. 361 


VIII. 












































PRECIPITATES.* 
aa : Prepared for Weighed 
Soluble in Contaminants. Weighing tyes sik 
Slightly soluble in cold, | NaCl and other salts (as Drying. KoPtCle 
more so in hot, H,O.| sulphates) insoluble in 
Solubility increased by | alcohol. Removed by 
alkali or acid, diminished | washing with H,O+ 
by Pte, or NagPtCle. NH,C1+ K,PtCle. 
As above As above. Ignition gently at first. Pt 
Addition of H,C,O,4 
aids reduction. 
In water. Less in alcohol | NaCl, and if long exposed | Ignition not above a KCl 
or strong HCl. to the air, organic dust. dull red. 
Moderately in H,O, much | Na2SO, or other non-vola- | Ignition over an ordi- K,SO, 
less in alcohol. tile sulphates. nary Bunsen flame. 
Same as KCi. KCl and other salts (as | Ignition not above a NaCl 
sulphates) insoluble in| dull red. 
alcohol. 
Same as K,SO,. K,SO, and other non- Same as K,SQO,. NagSO,4 
volatile sulphates. 
Mineral acids. Slightly | MgC,0,4,whichisremoved | Ignition, gently at first, CaO 
in Hy,C O4. by solution in HCl and] and finally over blast- 
reprecipitation. lamp. 
As above. As above, Addition of H,SO,4, CaSO, 


evaporation, and igni- 
tion. In presence of 


























C add HNOs3. 
H,0 containing CO,. In| BaCO, and MgCOs, if 
acids and in hot solution | much are present. 
of NH,Cl. Insoluble in 
H,O+NH,0H +(NH,4)o 
COs. 
Acids. Hot solutions, and. SiO, and Mg(OH).. Ignition, gently at first, | Mg,P.0O, 
slightly in cold H,O. finally intensely. In 
Insoluble in NH,NOszg. presence of C add 
NH,NOs3. 


Acids and ammonium | Usually unimportant for 
salts. Prevented by or-} purposes of separation. 
ganic salts. 
































Conc. H,SO,4, in strong } Alkaline and alkali- | Ignition. In the pres-| BaSO, 
hot HCl and HNOsz] earth chlorides, chlo-| ence of C the addition 
(dilute). In strong hot] rates,sulphates, nitrates, | of HNQsg is necessary. 
Fe,Cl, and in alkaline} basic, ferric, or aluminic 
or alkali-earth nitrates.| compounds. Repeated 
In citrates. boiling in wery dilute 

HCl assists in removal, 
but liable to dissolve 
some of the precipitate. 

H,O containing CO, and | MgCO, if much is present, 
acids. In hot NH,Cl.| and carbonates of the 
Insoluble in NH,OH+ fixed alkalies. 

(NH,4)2COs. 











“Properties of Precipitates,” School of Mines Quarterly, vol. x. 


302 













































































Ele- . Obtained by or 
ment. Object. Precipitated with— 
Fe Weigh- | Precipitant NH,OH. 
ing Addition of NH,Cl aids 
precipitation. 
Separa- As above. 
tion : 
Separa- | Precipitant NaC,H Oz. 
tion Filtered hot. 
Al Weigh- | Precipitant (usual) 
ing NH,OH. Best precip- 
itated by adding slight 
excess NH,OH, boiling, 
and passing H.S. 
Separa- Same as Fe. 
tion 
Cr Weigh- | Precipitant NH,OH. Ex- 
ing cess removed by boiling. 
Ti Weigh- | Insoluble form by boiling 
ing the solution acidified 
with H,SO,. 
| Separa- | Fusion and leaching until 
tion filtrate runs cloudy. 
Zn Weigh- Precipitant Na,gCQOs. 
ing 
Separa- | Precipitant H.S in boiling 
tion dilute HC,H;O,_ solu- 
tion. NH,Cl facilitates 
precipitation, 
Mn | Weigh- | Precipitant NaNH,HPO, 
ing in presence of amimo- 
nium salts, 
Separa- | Br from acetate solution. 
tion KCl1O, from __ boiling 


nitric-acid solution. 


Qn Se ee 


A MANUAL OF PRACTICAL ASSAYING. 


PROPERTIES OF 


Obtained or 


Precipitated as— Conditions of Solution. 



























































Fe,(OH). er and free from 

gv. 

Fe,(OH)., As above, 

Fe(OH)n(C,H3 | Dilute containing but 
2)6—” little free C,H3Q0g. 
Hot, but too long boiling 

should be avoided. 

Al,(OH), Neutral or slightly alka- 
line, containing prefer- 
ably NH,Cl. 

Al,(OH)n(C2H3 Same as Fe. 
Og)g—n No free acetic acid should 
be present. 

Cr,(OH)6¢ Absence of members of 
the (NH,).S group, and 
preferably all non-vola- 
tile salts. Solution must 
be neutral, 

H,TiOg; Dilute containing but 
little free H,SO,4. BCl 


and chlorides must be 
absent. HC,H3O, facil- 
itates precipitation. Pro- 
longed boiling also, 
Long fusion with NagCOg 


(x Na,O, TiOg) 
i at high temperature, 


NagTiOg 




















2ZnCQO3, Zn(OH), | Absence of caustic and bi- 
carbonate alkalies and 
ammonium salts, 


ZnS.H,O Alkaline or acid only with 
weak organic acid. Free 
mineral acids prevent 
precipitation (H2SO, 
least). Fe should be 
absent. 

















Mn must be entirely in 
manganous form, and 
Slightly alkaline. An 
excess of id a is 
necessary. Oxalates and 
excessive amounts of 
ammonium salts should 
be absent. 

Absence of HCl or other 
halogen acids. Also 
lower oxides of nitrogen 
or reducing agents. 
Boiling necessary. 





MnNH,PO, 


MnO, 










































































TABLES, 303 

PRECIPITATES. 

: : Prepared for Weighed 
Soluble in— Contaminants, Weighing by— rhs 

Mineral acids and solu-| Basic ferric salts, Cr,|Ignition. In presence Fe,O3 
tions containing citric,| P.,0,, Al, Mn, Zn, Co,| ofC,HNOg, or NH,NO, 
tartaric acids, etc., or | Ni, Mg, SiO g, etc: should be added. Vol- 
organic substances (as atile in presence of 
sugar). chlorides, 

As above, As above. 

In cold mineral acids.| Salts of fixed alkalies; 
Also in citrates and or-| SiO,g, P,O,, Al, Cr, Co, 
ganic substances. Insolu-| Ni, Zn, Mn, Cu, etc. 
ble in hot very dilute} Removed by resolution 
HGeH.Oo: and reprecipitation. 

Acids and fixed aikalies | Basic Al salts; SiO,,{|Ignition. Slightly vola- Al,O3 
Slightly incold|NHZOH: | Ps0,;, Al,\ Cr, Co, Ni,| tile in presence of 
Tartrates, citrates, su-| Zn, Mn, etc. Removed | NH,Cl. 
gar, etc., prevent precip-| by resolution and repre- 
itation. cipitation. 

Sameas Fe, except slight- Same as Fe. 
ly soluble in hot dilute 
EG lH.O>, 

Allacids in NaOH, KOH, Same as Al, Ignition. Cr,O3 
and slightly in NH,OH. 

Tartrates, citrates,sugar, 
etc., prevent precipita- 
tion, 

Soluble form same as Fe, | Fe,O3, AlpO3, SiO,, and} Ignition with addition TiO, 
(OH).. O, Fe,O3 and AlgOg3 of (NH4)2CO3. 

Insoluble form by fusion} removed by resolution, 
with KHSO, or boiling | reduction with ae 
with conc. HCl or| and reprecipitation in 
H,S0O,. presence of HC,H3,0, 

Acids. Slightly in H,O. | Fe,O3, acid-sodium  sili- 

: cate, alkali-earth carbon- 
ates, etc. 

Dilute acids, fixed caustic | Alkaline carbonate re-| Ignition; absence of C ZnO 
alkalies, bicarbonates,| moved by repeated | is necessary. 
and organic solutions. washing with hot H,0O. 

Fe,O3, AlgQOs, and SiO, 
removed by solution and 
precipitation of the ig- 
nited ZnO. 

Dilute HCl and HNOsg, | Mn, Co, and Ni sulphides, 
strong H.SO, when hot. | Removed by resolution, 
Free NH,OH retards} neutralizing, and repre- 
precipitation. cipitation. Fe if not 

; previously removed. 

Acids. Slightly in large | None if bases forming in- | Ignition. Gently at first. |. Mn,gP,0, 
excess of ammonium| soluble phosphates are 
salts. The influence of | absent and precipitate is 


ammonium salts is 
lessened by large excess 
of the precipitant. 


Dilute mineral acids (es- 
pecially HCl). Insoluble 




















































































































well washed. 


Salts of fixed alkalies, 
Fe,03 , ZnO 


in strong HC,H,0, and 


conc. HNOg. 





























304 A MANUAL OF PRACTICAL ASSAYING. 


PROPERTIES OF 




















Ele- : Obtained by or Obtained or was ; 

ment. Object. Precipitated mie Precipitated as— Conditions of Solution, 
Ni Weigh- Electrolysis. Ni Absence of all other 
ing (See Table VI.) metals of H,S and 
(NH4).S_ groups. Ni 
present as oxalate, sul- 
phate, or double am- 
monium nitrate, and ex- 

: cess of NH,OH. 

Weigh- | Precipitant KOH or Ni(OH),. Bases other than fixed 

ing NaOH. alkalies should be absent. 

Separa- | Precipitant H2S in weak NiS.HO, Absence of other mem- 
tion HC,H 30, solution. bers of ~ the) Hes) Jor 


(NH4)25 groups. NH,Cl 
aids precipitation. 


‘ 


Co Weigh- | Precipitant KNO, in solu- | 6{NO2,Co,(NOg), | Warm, containing only 





















































ing tion slzght/y acid with Co, Ni, and K salts, and 
HC.H30x¢. nearly saturated with 
KC,H 30.9. 
Weigh- Electrolysis. Co Same as Ni. 
ing (See Table V1.) ; 
Separa- Same as NiS.H,O. CoS,H,O Same as NiS,H,O. 
tion 
Cu Weigh- Electrolysis. Cu H.SO, solution contain- 
ing (See Table VI.) ing a few drops of HNO, 


preferable. Organic acids 
should be absent. 


Separa- | Precipitant H.S in dilute CuS Moderately strong HCl or 
tion acid solution. H,SO,. If “HNO, vis 
present, the solution 

must be cold and dilute. 





























Pb Weigh- Precipitant H,SOx,. PbSO, Excess of H,SO, and but 
ing little HNO, or HC 

NH, salts and salts of 

organic acids must be 


absent. 
Weigh- | Precipitant K,Cr,O, in PbCrO, Bi, Ag, Fe, and Ba shonld 
ing acetic-acid solution. be absent. Chlorides 


should be absent, and 
also alkaline  citrates, 
tartrates, etc. 














Separa- Precipitant H2S. PbS Slightly acid, neutral, or 
tion alkaline. Best precipi- 
tated in cold H,SO, 
solution. 
Ag Weigh- | Precipitant HCl in very AgCl Slightly acid with HNO, 
ing slight excess. free from chlorides. 
Separa- Precipitant NaBr. AgBr Same as AgCl. 


tion 


















































































































































TABLES. 305 
PRECIPITATES. 
aay : Prepared for Weighed 
Soluble in Contaminants. Weighing by— oe 

Readily in HNOg. Slowly | Co, Fe, and Zn, unless| Drying at gentle heat. Ni 

in strong (NH,4).C,Ox4. previously separated. (See Cu.) 
(See Table V1.) 

Mineral acids. In am-| Alkalies, Fe.O3, Al,O3, Ignition strongly. NiO 
monium salts, tartrates, | and SiO, from reagents. 
citrates, etc. 

Precipitation prevented | Sulphides of H,.S and 
by moderate amounts of | (NH,4).S groups, if not 
free acetic or mineral}| previously removed. 
acids. Soluble in mineral 
acids and KCN. 

H.O, acids NH, and Na|Caand Pbif present. K | Dissolve in dilute | 3K,SO, + 
salts. Insoluble in dilute | salts should be removed | H,SO,4,and evaporate | 2CoSO,4 
HC,H30, and alcohol. by careful washing, a a weighed vessel. 

: gnition., © 
Same as Ni, Same as Ni. Same as Ni. Co 
Same as NiS,H,O. Ni and other members of 
(NH4)oS group, if not 
previously removed by 
separation. 

HNO, and HCl. Deposit | As, Sb, or Bi, if HNOg, is | Washing with H,O and Cu 
prevented by Cl, too} not present. If HNOg,| then with alcohol. 
strong acid, or lower ox-| and Zn are present, Zn | Drying at a tempera- 
ides of nitrogen. will begin to precipitate | ture which can be 

as soon as Cu is all pre-| borne by the hand. 
cipitated. 
(See Table VI.) 

Hot dilute HNO, and/| Other members of the 
strong hot HCl. H.S group. 

Conc.* mineral acids; in| Other sulphates, which | Ignition. If C is pres- PbSO, 
Na,S.O3; in NH, salts, | are removed by washing] ent, treat with HNO; 
and especially those of | with very dilute H,SO4. | + H2SO,, evaporate, 
organic acids. and ignite. 

Moderately strong min-| Ba, Bi, Hg, and chro-| Drying on previously} PbCrO, 
eral acids; in hot NH,C,| mates. If much Fe is| weighed filter. 

H,O,. Insoluble in di-| present, possibly Fe, 
lute HNO. (CrO4)3. 

Dilute boiling HNO,; hot | Other members of the 
conc. HCl. In Na,S_,O3.| HeS group if present. 

Partially in strong hot | Chlorides of Pb and Hg} Ignition until the edges AgCl 


HCl or HNO3. Partially 
in alkaline and alkaline- 
earth chlorides. Readily 
in NH,OH, KCN, and 


excess of precipitant. 


if present in the solution. 


Volatile at a 
slightly 


fuse. 
temperature 
above dull red. 





306 
































A MANUAL OF PRACTICAL ASSAYING. 







































































Absorption with KOH, |Na,CO,, K.2CO;or 
CaOH Bi Na,CO3-+ CaCO, 





Ele- : Obtained with or 
ment. Object. Precipitated by— 
As Weigh- | Precipitant H2S in HCl 
ing solution, 
Weigh- | Precipitant MgCl, in am- 
ing moniacal solution con- 
taining alcohol. 
Sb Weigh- | Precipitant H2S in acid 
ing solution, or upon acidify- 
ing solutions of sulph- 
antimonite. 
Sn Weigh- | Precipitant H,S in acid 
ing solution or upon acidify- 
ing solutions of alkaline 
sulpho-stannate. 
P Weigh- |MgCl, in ammoniacal 
ing solution containing 
NH,Cl. 
Separa- Precipitant (NH4)gMoQ, 
tion and | in HNOsz solution heated 
Titration] to 80° C. Agitation 
facilitates precipitation. 
S,SO.,,| Weigh- | Precipitant BaCl, in hot 
S203, ing solution containing a 
SOg5 little free HCl. 
etc: 
EI Weigh- Precipitant AgNOs. 
ing 
Siand| Weigh- | By evaporation of acid 
SiO, ing solution to dryness and 
heating at 115° to 120° C., 
or by evaporation of 
H.SO, solution to fumes 
of SO3. 
C,CO,,| Weigh- 
etc. ing NaOH, or 
NaOH. 
N Weigh- PtCl, 














Obtained or 


Precipitated as— 





ASoS3 


MgNH,AsO, 





SbeS3 








PROPERTIES OF 


Condition of Solution. 











Acid with mineral acid 
(preferably HCl). 


Alkaline with NH,OH, 
containing a minimum 
of NH,Cl and 30 per cent 
of alcohol. 











—— 


Slightly acid and moder- 
ately dilute. - 








Moderately dilute and 
slightly acid. Precipi- 
tation promoted by 
acetates and interfered 
with by oxalates or ox- 
alic acid. 


12M00,(NH,) 
PO, + 4)3 





x H,0,SiOg 











(NH,)ePtCl, 








Same as Mg. 


Acid with HNOg,and con- 
taining an excess of 

H,NO, and _precip- 
itant. Chlorides, HCi, 
reducing agents and or- 
ganic acids should be 
absent. 


Same as BaSOx,. 














— 





Same as Ag, 





Should contain HCl. If 
much HNOsz is present, 
should be removed by 
adding HCl and boiling. 








Same as K,PtClg. 






































































































































































































































PABLES, 367 
PRECIPITATES. 
aa : Prepared for Weighed 
Soluble in Contaminants, Weighing by— mee 
Soluble in alkaline hy-| Other sulphides of H,S/| Drying. Volatile as As2S3 
drates, carbonates, and} group if present. ASqS3 upon ignition. 
sulphides. In KHSOg, 
in aqua regia, and in 
H,O+ Cl or H,O-+ Br. 
In warm acids. In H,O| Basic Mg salts, sulphates, | Dissolving the precip- | Mg,As,O, 
+NH,Cl Insoluble in| and other salts insoluble} itate in HNO, into a 
NH,0OH8H -+ alcohol. in NH,OH -+ alcohol. weighed vessel, evapo- 
rating, and _ igniting 
slowly at first. 
Moderately concentrated |S generally accompanies | Mixed with 50 times its Sb,0, 
acids (HCl especially). | the precipitate; removed | weight of HgO, and 
Tartaric acid assists pre-| by replacing the H,O by | ignited to dull red. 
cipitation. Dissolved by | alcohol, and washing 
fixed alkalies or alkaline | with CSg. 
sulphides. 
Moderately strong acids| Other members of H,.S | Heating moderately and SnO, ° 
(HCl especially). In| group,if present. Sepa-| slowly with free access 
boiling solution contain- | rated from SbeS,byadd-| of air. Addition of 
ing free HgC.O,. ing H2C,O04, and boiling. | HNOgaids conversion, 
Same as Mg. Same as Mg. Same as Mg. Mg,P,07_ 
NH,OH and_ alkalies. | Arsenio-molybdate, SiO, ,| For titration by dissolv- 
Soluble in HCland mod-| Fe,O3, and TiQOg. ing in NH,OH and 
erately strong H,SO, reducing by Zn + 
or HNO3. In hot H,O. H,SO,, or by acidim- 
Insoluble in very dilute etry. 
HNO, containing NH, 
3- 
Same as BaSQO,. Same as BaSQ,. Same as BaSQO,. BaSO, 
Same as Ag. Same as Ag. Same as Ag. AgCl 
Boiling caustic fixed al-| Insoluble sulphates, re-|Ignition after drying. SiO, 
kalies. By fusion with | moved by digestion with} When impurities are 
fixed alkalies (caustic or | conc. HgSQO,. Also| present is determined 
carbonate). Insoluble in| SnO,, Sb,O,,and TiO,g.| by loss on_ ignition 
H,O and acids (HF ex-| Sometimes Al,O, and} with HF and H2SOQ,. 
cepted). Fe,O3. In which case 
determine by loss. 
H,O and CO, from the| Absorption in weighed CO, 
atmosphere. Prevented | apparatus containing 
by suitable absorption | suitable absorbents. 
apparatus. 
Same as K,PtClg. Same as KgPtClg. Ignition to Pt. N24 


(See K,PtCl,.) 





A MANUAL OF PRACTICAL ASSAYING. 


308 








FEOrStEN 
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piepuris NOx 
JO Ssooxy [euiou-jje Py 
XO"D° 
SONSYV [BWION 
FOOW*(*HN). 
uorjnjos uIUUe Ty [eUlON 
piepueys 8O*uy*y 
jo SSIIXY [eW1oON 
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&(FOS)®aq SNOM [ew40N 
EN; 


SONSY eulldeg | IGeN [eWwION 


IOWeN ss, 
FONS3V ame 


*JOJLIIPUT 





IORFN [ewson 


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ay} pue 4*O*H2DE] Jo ssooxe 14si\s 
ew Sulurejuos %4O*p{so)ng Jo uon 
-njos & woly Jy Aq pajeqdiseid ng ayy 


‘poppe HO'HN fo 
ssooxa ue pue §ONF UI! pedjossip ny 


‘2A0qe se owes 


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pue *°O"H*O°HN U! pealossip *OSdd 


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pue ‘joyooye Surureyuod uOoTIN[OoS 
ploe-ota0e ul poyeldiseid *O%Dqq 


‘“aAOge SB QUIeS 


“oAOge se sWes 


‘Iq pue 19 “qd ‘8H Wwodj so1j pue 
‘proe ApIYSI[s ‘ayN[Ip ‘WvM oq pjnoys 
O°H+PONH $Y! padlossip 4aaIs 


*uOTINfOS Jo uoT}Ipuod 


‘ORS IEN et ED 
= Osten + 12+ 18ND 
HOTHN? 


+ ®ON MZ + 2N290990%( NOM) = NOUV 
+ OF HE + ®FONTHNIO(ND®H?N) ng 








“O° H*OH2 + O° HOM TF °O19ddz2 
=H Le OVI 1 OH ode 


29° H*D"HN2 + OOINdd 
= *O0m"V HN) + (6O"H9)dd 
O*H8 -++ *OSUNZ 
+tosty +%0901-+ 'oSqd$ 
= §o*un*y +’ OS*H8 -+ *0°D4d% dd 





‘ONY +SNO8V =SNOM + °ONSV 
®ONPN + JQ8Y = Ige®N + SONSYV 


SONPN + 108V = IOeN + *ONSV 3Y 


‘uolOLaYy ‘yuoWAT | 





‘SNOILVNINUALAG DINLANNTOA 


ie a1 vs. 











‘uonesn Aq 
paieudisaid *Quyy pue ‘QuzZ Jo ssao 
prepueys 8O*uN ey “Xo UP YIM paZi[einau st UolNjos ros*Hz + 'OS*a + *OUINS 
"JO ssooxy [emsou-prugy | ey} ‘*OS*H Url paajossip st UW eyL = O°H2 + °O*UW? a +°OSUNE 


“O*uW* y Aq pourutiaiap *O#D*H Jo 
SS99X9 JY] pue 6'GO%9%F_ Jo Ainuenb 














piepueis ®OcU UMOUY & pue *~OS%;y Jo Ssooxo ue *OSUW + OF HZ + #002 
JO ssaoxq [eWION Ul paafossip si fQuy pereiudrooid ayy = '0°0°H +-*’OS*H +°OUN UW 
"IOH Jo ssooxe YSI[s 
°N°O24"H eB ulejuod pue ‘aq pue “pO ‘UW ION? + °N°D9S UZ 
°2OFH*D)N [eUIoN ‘nd Wodj s01J aq JsnW UOIINIOS 9UIZ = *N®*DQ9q*Yy + 2IDUzZe uz 
< OH 
Q JO ssooxo ue ulej]U0D pue ‘qs pue 
Sa) ‘sy “I9 ‘IL wos oa1J oq IsnuI UO) 
N 40°19° 3 “NJOS “*1QuUS 101g + UZ ‘UZ YUM OTHE +7199 Ise + 12a 
°N°D°4° [ewsoNn psonpet pue [DH Ul paalossip St a7 = IOHVI+ 40%9*a + 410949 
*FOS*H Jo ssaoxo Ue UIe}JUOD pue 
‘qS pue ‘sy ‘ID ‘I, Wosj. ve15 2q 53M Sho ge 
prepueys °O*UN? isn uoNNfog Iq -- UZ 10 UZ YUM *osuNz + 'OS*s + &(°OS)F9A$ 
JO SSoOxy [eWION peonpos pue ’OS*F{ Ul PoA[OSsIp SI oY = '9S*H8 + *O2UW?M + 'OS24OI oq 
"191WM WIM YIM Poinfip pue 
SNO'HN SONH Jo ssooxe 1Y8i[s @ UT poAtos ONME + OSV°H +SNODZVE 
®(FOS)*ea 10 ‘SNOW “SIP SI 'Osy*sy paieidioid oy = SNOME + °ONHE ‘Posy'syv SV 





‘juasqe oq ISNUWI Iq pu ND °99 
"NPD" — | O8T_01 OFH IM pornyip pur [OH loa? + °N°D2H "PD 
*FOPH®D)A| = [eWION JO Ssaoxo IYSI[S B Ul PeATOsSIP SPO = *N*50q" + *1OPO2 PO 








UOTIN[OS YIIVIG | Jy [ewWION 


*OOW?("HN) 


ursfeqiydjousyd | *ONH [ewion 


[ewsou-jleyy 





A MANUAL OF PRACTICAL ASSAYING. 


jewsou-jjey 


‘doIjN[OS piepueis 





370 


‘aintip Ajaiesa 
“pow pue ‘*ONH yim proe Apysis 
9q PINOYS aplsolyo ayi jo uonyjos ayy, 





‘uoljesqyy Aq 
(IOH UL SPO 241 Jo uoNnNlos 4a7ye) 
peuluiajap SI Spd se poulquioa ¢s 
e4L "“OSPD jo uonnjos ourlexye 
ue Aq paqiosqe st S*fy paajoae ayy, 


‘uoleiy Aq paurwiaiap *OSqg 
SB poulquios qq ay) pue ‘*(®&ON)qq 
Aq *ONH Yum ploe Apysis voy 
-njos & wodj payeidiseid si §Qsg ayy 





"ATjaunpexye Aq pourwssjap F}OeN 
JO SS90X9 oY] pue ‘FYOeN Piepuris 
jO ssaox9 Ue YIM pajeal si 





®ONH + 198V = *ON8V + 10H 


S+1IHz=12+S*H 


20°H*D’HN2 + 'OOWdd 
= 'OOW*(HN) + *(®O%H*0)4d 


"Od°CHN)'OOW21 parendioaid ayy | OHI+ 'OOW*eN = HOPNZ + *OOW 


‘uorjeiq1) Aq pourutiajap uay) st 
StO*'OJ poonpal ayy ‘uz Aq paonp 
“21 FQOW 24) pue ‘papper si *OS* Hy 
JO ssaoxa ue ‘FTO? HN UI poajossip si 


O*HZz01 
+ °'OS* HVE + FOSUINE9 + FOOWOZI 


*Od ‘*(’HN)®OOWZI poreidisaid auL |= *OS*H 201+ 28 O*upy? yhE+8'O2t0pol 





"UOT}RINT} 
Aq paulwiaisp *O%5*~_ pauiquios 
ay} pue‘O*H JOY YW painyip sr 
uoTInjos ay ‘’OS* FT Jo ssaoxo ue ul 


PPATOSSIP SI FO*DLD parieydisoid ayy 





‘UOI}N[OS Jo uolIpuoy 





o*H8 + 


2992+ 'os*y + 'OSUNZ + *OSPFDS 





= *otu?y + *'OS*H8 + °O%D80§ 





UOTOvIY 





(7702109 )—SNOILVNINUALAG DINLANNTIOA 








APPENDIX A. 





MELTING AND REFINING GOLD BULLION. 


THE melting and refining of gold bullion and the prepara- 
tion of gold amalgam for retorting are operations which appear 
to be imperfectly understood by many mill superintendents, if 
one judges by the frequency with which extremely base bullion 
is deposited at the government mints and assay offices. 

Deposits of gold bullion may be classed as follows: 

Grains, generally the result of placer washing. The gold is 
usually quite fine and free from impurities other than sand. 
Placer gold frequently contains small quantities of lead and 
occasionally sulphides, especially if derived from streams below 
stamp mills. Another class of grains are those derived from 
the washing of small pockets of very rich ores which are some- 
times encountered in veins. These frequently carry pyrite 
and other minerals which were associated with the gold in 
the ore. 

Amalgamated grains, generally derived from placer wash- 
ing. As many placer miners working on a small scale have 
but imperfect facilities for retorting the amalgam, these grains 
frequently contain mercury in addition to sand and clay. 

Retorts, generally the result of stamp mill operations. If 
the result of the treatment of free ores these are generally 
quite free from impurities other than sand. If the result of 
the treatment of sulphide ores they frequently contain lead, 
copper, arsenic, and sulphides. The retort gold from Gilpin 
county, Colorado, while generally the result of the treatment of 
sulphide ores, is usually quite free from large amounts of these 
impurities, showing care in the preparation and retorting of 

371 





Ve APPENDIX A. 


the amalgam. Retorts are occasionally received which con- 
tain large quantities of water and mercury, showing great care- 
lessness on the part of those intrusted with the preparation of 
the bullion. The base character of retorted bullion is some- 
times due to the employment of foul quicksilver in milling. 
As quicksilver is readily purified, and as the use of foul 
“quick” invariably results in the loss of gold, this practice 
cannot be condemned too severely. ; 

Bars, which may be the result of amalgamation, chlorina- 
tion, leaching, smelting or placer washing. The bars from 
amalgamation usually contain the same impurities as the re- 
torts, unless they have been subjected to thorough refining 
during melting, which is not generally the case. Bars from 
chlorination works generally contain copper, sulphides (where 
sulphuretted hydrogen is the precipitant employed), iron (where 
ferrous sulphate is the precipitant employed), and more or less 
lead. Arsenic is also a constituent of these bars from some 
works. 

Bars from leaching works usually contain the same im- 
purities as those from chlorination and also zine (where zinc is 
the precipitant employed, as is usual where the cyanide process 
of extraction is used). These bars are frequently very base 
and difficult to refine. 

Bars from smelters may be divided into two classes: parted 
or fine bars and unparted bars, the latter frequently being un- 
refined. The parted bullion generally contains no impurities 
worth mentioning, small amounts of silver and copper, to- 
gether with the gold (usually over 990 fine), constituting the 
bullion. Occasionally small amounts of lead (sufficient to 
render the bullion brittle) are present. Unrefined bullion from 
smelters frequently contains copper, arsenic, lead, and various 
elements which were constituents of the ores. 

Jewelry and old plate, which is generally deposited in the 
form of bars or kings. These usually contain considerable 
amounts of silver and copper, but are otherwise quite pure. 
Iron (from watch springs, etc.) is sometimes present. 

All of these deposits, except the parted bars and those 


APPENDIX A. Vee 


derived from chlorination and leaching, contain considerable 
amounts of silver and require parting prior tocoinage. These 
are the principal impurities, although other elements, as bis- 
muth, antimony, tellurium, etc., are frequently present in small 
quantities. 


EFFECT OF IMPURITIES. 


Antimony, arsenic, lead, sulphur, tellurium, and zinc ren- 
der the gold brittle and unfit for rolling, even when present in 
such small quantities as 5,455 part. Zinc, when added to gold 
in large quantities, produces a ductile alloy. 

Iron, aluminum, nickel, cobalt, platinum, palladium, and 
rhodium form ductile alloys with gold. 

The presence of lead is indicated by the fracture, which is 
granular and has a silver-white lustre. The fracture of bullion 
containing arsenic is the same except that the color is a gray- 
ish white, resembling the color of metallic lead. The fracture 
of bullion containing zinc is crystalline to granular, and has a 
dirty-white color ; such bullion isseldom homogeneous. Bull- 
ion containing sulphides has a dirty dark-gray granular frac- 
ture. Small amounts of tellurium render the bullion crystal- 
line, the fracture resembling the crystalline structure of 
metallic tellurium. 

When the bullion contains lead, bismuth, and zinc there is 
a liquation, or separation, of these metals towards the outside 
of the bar on casting. 

Iridium and osmium separate to the bottom ‘of the melt. 

Platinum separates to the centre of the bar. 

If the bullion is free from impurities other than silver and 
copper, simple melting is all that is necessary in order to pro- 
duce a ductile and homogeneous bar. Should other impurities 
be present they must be removed by refining. 


MELTING. 


The bullion is melted in clay, sand, or graphite cruci- 
bles. It is usual to place the crucible in which the melting is 


374 APPENDIX A. 


performed inside of a larger graphite crucible in order to avoid 
danger of loss should the melting-pot crack or break. 

A wind furnace using coke or charcoal—the latter is prefer- 
able—serves all purposes, but where many melts are made the 
gas furnace is to be preferred on account of the facility with 
which the temperature can be controlled. 

The crucible should be heated gradually in order to avoid 
its destruction by cracking, and finally at a high temperature. 

The bullion is now introduced, the crucible is covered, and 
the temperature is raised. A plumbago stirrer is placed in the 
furnace so that when the bullion is melted the stirrer will be 
hot. This stirrer is a bar of plumbago about 8 inches long, 1} 
inches wide, and # inch thick, and is slightly curved and flat- 
tened at one end to facilitate the removal of slag. When the 
bullion has melted down and is perfectly fluid the cover is re- 
moved from the crucible. If pure, the surface of the melt 
should be perfectly clear, and present the appearance of a 
mirror. If not clear, refining is necessary. If clear, the melt 
is thoroughly stirred when it is ready for casting. The cruci- 
_ble is removed from the furnace and its contents are quickly 
poured into an iron mould which has previously been heated 
and greased with beeswax. In order to avoid loss by spatter- 
ing, the mould should not be filled more than two thirds. The 
mould is covered, and as soon as the bullion solidifies the bar 
is turned out and immersed in a bath of dilute sulphuric acid. 
This operation, called “ pickling,” serves to remove any slight 
stain from the surface of the bar, and gives it a handsome ap- 
pearance. Some operators use a dilute solution of nitric acid 
for this purpose. Should the bar show slight sulphide stains 
they may be removed by washing with a dilute solution of 
potassium cyanide. After pickling, the bar is washed in water, 
and any adhering slag is removed by hammering and washing. 


“REFINING. 


Impure bullion may be refined by fluxing in the crucible, 
by cupellation, or by parting in acids after melting with suffi. 


APPENDIX A. 375 


cient silver to insure parting. Parting is generally preceded 
by cupellation or crucible refining. 

Crucible Refining.—After the bullion has been melted as 
above, it is subjected to the action of certain fluxes for the re- 
moval of the impurities. Sand is removed by the addition of 
borax-glass, or borax-glass and sodium bicarbonate, to the melt, 
the resulting slag being lifted off with the stirrer. The stirrer 
should be of the same temperature as the furnace, in which it 
should remain throughout the operation. Iron and black sand 
are removed in the same manner. When much iron is present 
it may be removed by fluxing with sulphur. After the gold is 
melted sulphur is thrown around the sides of the melt, care 
being taken to add the sulphur to the sides of the melt. 
Should the sulphur be thrown on the centre there is liability of 
loss of gold, owing to the violent action which ensues. The 
temperature should not be much above the melting-point of 
the bullion, as otherwise there will be an undue loss of 
sulphur. The sulphur is stirred into the melt with the plum- 
bago stirrer, and forms iron matte, which rises to the surface. 
The operation is continued until all the iron is eliminated as 
matte, when the bullion and matte are cast. The matte will 
be found on the surface of the bar, and is readily removed. 
This matte should be fused with borax and soda, the result of 
the fusion being a button of bullion and clean matte, which 
may be discarded. The button and bar are now melted to- 
gether with nitre and borax, the result being a clean bar of 
bullion. As long as the melt contains iron but little silver 
sulphide will be formed; hence, as soon as the iron has all 
been converted into matte the addition of sulphur should be 
discontinued. 

Lead is removed by the oxidizing action of nitre which is 
thrown on the surface of the melt from time to time. Borax- 
glass is added with the nitre, to stiffen the slag and render its 
removal easy. Towards the end of the operation the surface 
of the melt presents a play of colors as in cupellation, and after 
this ceases fine threads may be seen continually crossing each 
other. The lead is now nearly all removed and the bullion is 


ae an ee aed 


376 APPENDIX A. 


liable to bubble or boil at this stage, but soon becomes quiet 
and perfectly clear, when it is ready for casting. Small quan- 
tities of lead are readily removed by the addition of oxide of 
copper, but some refiners object to the use of this reagent, as 
it introduces copper into the bullion. Should the amount of 
lead present be large, the oxidation by nitre will be tedious. 
When large quantities of lead, arsenic, or sulphides are present, 
bichloride of mercury may be used to advantage. The salt is 
broken into small lumps, which are thrown on the melt from 
time to time. The bichloride sinks into the melt, where it is 
decomposed, the liberated chlorine permeating the liquid mass 
and rapidly oxidizing the impurities. This reagent should 
never be used except where the furnace is provided with a wide 


hl 
f 


throat, a strong draft, and a hood to carry off any fumes which . 


may escape. On account of the dangerous nature of the fumes, 
this reagent is not largely used. Ammonium chloride is also 
used, but its action is much less rapid than that of the mercury 
salt. At the Royal Australian mint chlorine gas is forced 
through the liquid melt both for the removal of impurities and 
silver, the chlorine oxidizing the impurities and converting the 
silver into a chloride which rises to the surface. 

Arsenic is removed in the same manner as lead, it rising to 
the surface of the melt in the form of small, oily globules. 

Sulphur is removed in the same manner as lead and arsenic, 
but should the amount present be large the operation will be 
tedious and the following method may be adopted to ad- 
vantage: Prepare some strips of strap iron and as soon as the 
bullion is melted introduce them into the crucible. The iron 


decomposes the sulphides, forming an iron matte, which rises. 


to the surface. The matte is removed by skimming and is put 
aside for future treatment. This treatment is continued until 
the sulphides are all decomposed, when the bullion and slag 
are poured off into a mould. After chilling, the matte is re- 
moved and added to the skimmings, the whole being melted 
in a crucible, together with borax to recover the shots of gold 
which it contains. The result of this melt will be a king of 
bullion and clean matte or slag which may be discarded. The 


APPENDIX A. 377. 


bar and king are now melted with nitre, and the small amount 
of sulphides present are removed by refining with nitre and 
borax. The result of this melt is generally a refined bar, al- 


though a third melting with nitre is sometimes necessary. 


Platinum is partially removed by the action of nitre, some 
passing into the slag, but the greater portion remains with the 
gold and must be removed by subsequent acid refining. 

Iridium and osmium, commonly called osmiridium, as the 
metals occur together and remain together during treatment, 
may be removed by fire refining. The bullion is melted and 
allowed to remain in the crucible for half an hour at a high 
temperature. The osmiridium liquates and sinks to the bottom 
of the crucible. The furnace is then chilled and as soon as the 
bullion solidifies it is turned out of the crucible. ‘The osmirid- 


ium is found at the bottom, alloyed with gold and silver, and 


is cut off. As the osmiridium settles better from an alloy 
consisting chiefly of silver, the rich buttons are repeatedly 
melted with silver, the lowest portion being cut off each time. 
The alloy finally obtained is granulated and parted, the silver 
passing into solution and the osmiridium remaining behind, 


together with the small amount of gold remaining in the alloy. 


Antimony is best removed by treatment with metallic iron, 
as in the case of sulphides. 
Another method of crucible refining which is sometimes 


adopted is as follows: The bullion is melted in a plumbago 


or clay crucible, and when fluid the surface of the melt is 
covered with bone-ash. Small quantities of lead are forced 
into the molten mass, usually from 0.1 to I. per cent. of lead 
being sufficient. The lead is thoroughly stirred into the mass, 
and nitre is added as an oxidizing agent from time to time. 
The effect of the nitre is to oxidize the lead and the impurities | 
which rise to the surface and are absorbed by the bone-ash. 
Sometimes oxide of copper or metallic copper (about twice 
the weight of lead used) is added to advantage, especially if 
the bullion contains zinc. The operation is virtually that of 
ccupellation. | 


378 APPENDIX A. 


Other impurities are generally present in small amounts and 
arerreadily removed by nitre and borax. 
Potassium nitrate is the reagent generally employed, as the 


commercial sodium salt is not nearly as pure and generally 


contains considerable chloride of sodium. Should much silver 
be present, chloride of sodium is liable to result in loss by 
volatilization. 

The refining is preferably performed in clay or sand cruci- 
bles. When only graphite crucibles are at hand, or where the 
melt is too large for the clay or sand crucibles, the refining 
may be carried on in a graphite melting-pot, the corroding 
effects of the nitre and slag on the graphite being lessened by 
throwing bone-ash on the surface of the melt. This collects. 
around the sides, absorbs oxides, and forms a ring around the 
sides of the crucible which effectually protects them. 

Refining by Cupellation.—When large amounts of lead, 
arsenic, sulphur, etc., are present, crucible refining is slow and 
tedious, and cupellation may be substituted to advantage. 
Where a cupel furnace is not at hand a very good substitute 
may be readily arranged as follows: Saw off the lower part of 
a graphite melting-pot about four inches above the bottom and 
tamp in with bone-ash. Hollow out the cupel to receive the 
metal and place it in the throat of a wind furnace provided 
with a good charcoal fire. When the cupel is hot introduce 
the bullion, together with sufficient lead, place the cover on 
the furnace, and give the fire a strong draft. As soon as the 
lead begins to drive, the cover is removed from the furnace, 
the operation requiring no further attention other than to keep 
the temperature at such a point that there is no chance of the 
metal solidifying or freezing before the lead is all removed. 
Should the metal chill before the lead is entirely removed, the 
small amount remaining may readily be removed by subse- 
quent crucible refining. 

Where a large muffle furnace is at hand cupellation may be 
readily carried on in the muffle by preparing some large 
cupels 8 to 10 inches in diameter, which are placed in the 
muffle, and when hot the bullion is introduced, together with 


we 2» 5 


APPENDIX A. 379 


sufficient lead to eftect cupellation. The cupels are made of | 
bone-ash ‘thoroughly tamped in around a circular iron ting 
and subsequently thoroughly seasoned by slow drying. A 
good substitute for the iron ring is a circular section sawed out 
of an old graphite melting-pot. In this way from one to two 
hundred ounces of bullion may be easily and quite thoroughly 
refined. The cupei bottoms should be saved, as they are 
liable to absorb precious metals, which is especially the case 
when the bullion contains much zinc, copper, sulphides, and 
tellurium. 

Acid Refining.— Whilst acid refining or parting is usually 
preceded by crucible refining or cupellation, this method is 
sometimes adopted preliminary to fire refining. Treatment 
with sulphuric acid prior to melting is especially efficient for 
the removal of zinc from the gold slimes, or precipitate, ob- 
tained on zinc shavings in the extraction of gold by the cy- 
anide process. Whilst the action of sulphuric is slower than 
that of hydrochloric acid, and the sulphate solution is more 
tedious to filter, the use of the former acid is preferable on ac- 
count of the liability of loss of gold owing to the generation of 
free chlorine during the treatment with hydrochloric acid. 
Commercial hydrochloric acid is also liable to contain some 
nitric acid, which would involve loss of gold if present. Direct 
treatment of the slimes with acid is unsatisfactory, owing to 
the loss of gold due to the evolution of hydrocyanic acid and 


the formation of gelatinous cyanide of zinc, which latter 


renders the filtration extremely tedious and difficult. If the 
slimes are previously treated in a filter press (Johnson’s*) the 
soluble cyanide salts may be readily separated by washing, the 
bulk of the zinc being thus removed in solution. The residues 
are now spread in thin layers on iron trays, and dried and 
heated at a barely perceptible red heat in the muffle or the flue 
of a furnace. The carbon, zinc, arsenic, etc.. ignite readily, 
being in a fine state of division, and the roasting proceeds 
with regularity to the bottom of the layer without stirring. 








+ ‘the Lixiviation of Silver Ores. Stetafeldt. (Scietif. Pub. Co.). 


380 APPENDIX A. 


The resulting mass is oxidized, porous and aggregated some- 
what into granules. This mass consists principally of oxides 
of lead and zinc with gold and silver. It is now ready for 
treatment by heating with dilute sulphuric acid, the zinc pass- 
ing into solution, leaving the gold and silver behind, together 
with lead sulphate. This residue is easily filtered and washed, 
when, after drying, it is fused with nitre, borax and bicarbonate 
of soda. The method of crucible cupellation may also be ad- 
vantageously used. , 

Acid refining in nitric or sulphuric acids, after melting with 
sufficient silver and granulating, is extremely efficient, but as 
this method requires a special plant and is moreover described 
in the standard works on the metallurgy of gold and silver,* it 
is unnecessary to discuss it here. 

Toughening.—All bullion requires toughening to render it 
perfectly ductile. This is usually accomplished by melting 
with nitre and borax, with potassium bisulphate and borax, or 
by the addition of bichloride of mercury to the melt. It may 
also be accomplished by forcing chlorine gas through the 
molten mass or by pouring the molten gold in a thin stream 
through the air from a height of three or four feet. 

Bullion which has been thoroughly refined will consist of 
an alloy of gold and silver, with possibly some copper, and 
should be ductile and perfectly homogeneous. Brittle bullion 
may be homogeneous, but more frequently samples taken from 
different parts of the bar will show considerable differences in 
fineness. 

SAMPLING. 


Either of the following methods is to be recommended: 

Cutting off diagonally opposite corners with a chisel. These 
clips are pounded on a polished steel anvil and passed through 
a set of hand rolls until rolled into the form of a ribbon. 








* The Metallurgy of Gold and Silverin the United States. Egleston. (Wiley 
& Sons.) 

Precious Metals in the United States. Report of the Director of the Mint. 
Washington, 1880. 

The Metallurgy of Gold. T. Kirk Rose. London, 1894. 


APPENDIX 7A. 381 


Drilling, it being preferable to take four drillings as indi- 
cated in the sketch. Equal amounts of the a, a’ drillings are 
mixed together for the asample. The 8, b’ drillings are treated 
in the same manner for the b sample. 

Where the bar is ductile and perfectly homogeneous the 
first method is preferable as the sample is in better condition 
for rapid weighing out. 

Where the bullion is brittle and probably not homogeneous 
samples taken be the second method will more truly represent 
an average of the bar. 

Another method which may be adopted to advantage in 
the case of very impure bullion is to take dip samples from the 
molten mass in the crucible. One sample is taken just before 
pouring and after skimming. A second sample is taken when 
nearly all the bullion has been poured. A convenient vessel 
for taking the sample isa small Hessian crucible or a plumbago 
cup which is made especially for this purpose. Each sample is 
granulated by pouring into water, the granulations being kept 
separate. 





Fic. I. Fic. 2. 


APPENDIX B. 


THE PREPARATION OF PURE GOLD AND SILVER. 


PURE gold and silver are necessary in the assay of gold 
bullion (Part III., Chapter III.) and are also frequently used in 
the assay of ores and metallurgical products. Pure silver may 
be purchased from dealers, but gold of sufficient purity is not 
readily obtained. . 

The Preparation of Proof Gold.—As pure gold as is ob- 
tainable should be taken for the preparation of the proof ma- 
terial. The best material to use is the gold cornets obtained in 
the assay of gold bullion and the parted gold resulting from the 
assay of gold ores. These cornets are about 998 fine and the 
other 0.002 parts being silver. Should such material be unob- 
tainable, material of similar quality may be prepared from gold 
coin or refined bullion as follows: Weigh out the gold and for 
each part of gold add 2% parts of pure silver and from 10 to 
16 parts of pure lead. Cupel, and after flattening the result- 
ing button of gold and silver, anneal it at a red heat. The 
button is now passed through the flattening rolls until reduced 
to a ribbon of about the thickness of a fine visiting card. The 
ribbon is annealed, rolled into a coil, introduced into a flask 
containing nitric acid of 27°. B. and boiled for 20 minutes. 
The solution is poured off and fresh acid of 32° B. is added in 
which the ribbon is boiled for 20 minutes. The acid is poured 
off and the ribbon is washed several times with distilled water. 
In this treatment the copper and other impurities are removed, 
the ribbon consisting of gold and a small amount of silver. 

The gold taken is weighed and introduced into an Erlen- 
meyer flask and aqua-regia is added. About 4 fluid ounces of 

382 


APPENDIX B. 3383 


acid will be required for each Troy ounce of gold taken. The 
acid fs added gradually, and after all is added the flask is heated 
over a Bunsen burner protected with a piece of asbestos card- 
board. When the gold is all dissolved the contents of the 
flask are slightly diluted with distilled water and allowed to 
stand for a few hours to allow the separated silver chloride to 
settle. The clear solution is now decanted off into a large 
porcelain evaporating dish, care being taken to retain the silver 
chloride in the flask. The contents of the dish are evaporated 
until all the nitric and most of the free hydrochloric acid is 
expelled. At this point auric chloride will commence to sepa- 
rate out. The solution is largely diluted with distilled water 
and filtered through a heavy filter paper into a large glass 
flask. The solution in the flask is diluted with distilled water 
until the flask contains as many litres as there are ounces of 
gold in solution. The neck of the flask is covered and its con- 
tents are allowed to stand for five or six days in order that the 
silver chloride may settle and separate. The clear solution is 
now decanted through a triple filter paper into a glass flask. 
The precipitate and a small portion of the solution should be 
allowed to remain in the flask, for if washed onto the filter, 
there is danger of silver chloride passing through into the fil- 
trate. The filtrate is heated nearly to boiling and an excess of 
a saturated solution of oxalic acid is added. The flask is 
allowed to stand ina warm place over night, when, provided 
sufficient oxalic acid was added, the solution will be found to 
be colorless, showing that all the gold has been precipitated. 
‘The solution is poured off and the precipitated gold is washed 
several times with warm distilled water. It is now washed with 
strong ammonia-water to remove any trace of silver chloride 
which it may contain, and after pouring off the ammonia, again 
with water. It is finally washed with warm dilute hydrochloric 
acid, and after pouring off the acid, again with distilled water 
until the washings are sweet. The gold is now washed over 
into a porcelain dish, in which it is dried. The dry gold is 
melted in a clay crucible, in which some borax has previously 
been fused to glaze the sides, its surface being protected by a 


384 APPENDIX B. 


cover of borax-glass. When fluid a few crystals of nitre are 
added and stirred into the melt with a hot plumbago rod. 
The melted gold and slag are poured into a hot iron mould 
which has previously been well greased with beeswax, and as 
soon as it solidifies the mould is turned over and the bar is 
plunged into cold water. This serves to remove most of the 
slag, the remainder being removed by hammering and rubbing. 
The bar is passed through a set of flattening rolls until rolled 
into a ribbon of convenient thickness. The ribbon is rolled 
into a coil which is boiled in dilute hydrochloric acid and, 
after pouring off the acid, it is washed with distilled water. 
The gold is finally dried and heated to redness in the muffle. 

In this manner the author has frequently prepared several 
ounces of gold which was from 999.95 to 999.96 fine. 

Should the gold used contain platinum it will have to be 
removed. To remove the platinum concentrate by evapora- 
tion the clear solution of chloride of gold free from silver, add 
an excess of absolute alcohol and pure potassium chloride and 
allow to stand at least 24 hours. Potassium platinochloride 
will separate and may be removed by filtration. The alcohol 
is now expelled by evaporation when the solution is treated as 
before. 

Should the gold contain small amounts of copper it may be 
removed from the solution by the addition of caustic potash, 
but as there is always danger of its incomplete removal the 
above method of refining by cupellation and parting is prefer- 
able and is more rapid. 

The Preparation of Silver.—In a laboratory where many 
gold assays are made there is always a supply of chloride of 
silver on hand as a result of the parting operation, the nitric 
acid solution containing silver nitrate being decanted from the 
gold into a glass or stone vessel containing salt (sodium chlo- 
ride). This silver chloride is washed with water until the wash- 
ings show only a faint trace of chlorides. To the vessel con- 
taining the silver chloride there are now added several strips 
of sheet zinc (4 ounces of zinc for each 10 ounces of silver will 
be sufficient) and then some sulphuric acid of 60° B. The 


APPENDIX B. 385 


vessel is allowed to stand over night, and if sufficient zinc and 
acid were added, the silver chloride will be found to have been 
all converted into cement silver. Should any zinc remain un- 
dissolved, more sulphuric acid is added to effect its solution. 
The cement silver is washed with water until the washings 
are sweet and is then dried. It is melted in a plumbago cru- 
cible, the silver being kept covered with powdered charcoal 
during the melting. Should the silver need refining, this is 
accomplished by the addition of nitre and borax-glass. 

The melt is cast into a bar 12 inches long, 13 inches wide 
and # inch thick. 

For the silver used in the gold bullion assay a great deal of 
time and labor may be saved by running the bar through a 
set of flattening rolls until it is reduced to the proper thick- 
ness. The rolled strips are now run through a punching 
machine which punches out disks of definite weights. In this 
manner disks of silver weighing anywhere from 500 milli- 
grammes to 25 milligrammes may be cut. They will be found 
extremely convenient for inquartation of the alloy. 


APPENDIX C. 


LOSSES OF GOLD AND SILVER IN@ THES i 
Velaeler gun de 


AS this is a question of considerable commercial importance 
as well as of scientific interest, a review of the results bearing 
on the subject, as recently obtained by the author and others,* 
is of interest in connection with the chapters on the determina- 
tion of gold and silver in ores and metallurgical products. 

The losses of gold and silver in the fire-assay are due to 
volatilization and slag absorption during scorification and 
fusion, and to volatilization and cupel absorption during cupel- 
lation. The following also have an influence on the accuracy 
of the results: 

Inaccuracy in weighing out and weighing back. The small 
milligramme weights used in weighing back the gold and silver 
beads are frequently far from accurate. Every assayer should 
thoroughly test each set of weights used, as those purchased 
from dealers are occasionally far from accurate. 

Should the lead buttons contain much arsenic, antimony, 
copper, sulphides, etc., the cupellation should be started ata 
high temperature. The only safe method to adopt is to start 
the cupellations ina hot part of the furnace, and as soon as 
cupellation commences bring the cupels forward. Where 
impurities are present the results will be low unless the cupel- 
lation is commenced at a high temperature. After cupellation 
is thoroughly started the cupels should be brought forward in 











* Furman: Trans. of the Am. Inst. of Mining Engineers, Voi. XXIV, pp. 
735, 871, and 874; J/éid., Vol. XXV. Le Doux: Jdid., Vols. XXIV and XXV. 
Mason and Bowman: Journal of the Am. Chem. Society, Vol. XVI, p. 313, 
May, 1894. Dewey: Journal of the Am. Chem. Society, Vol. XVI, p. 505, 
August, 1894. 

386 


APPENDIX C. 387 


the muffle so that the cupellation is continued at compara- 
tively a low temperature, and so that the cupels show feather 
litharge. 

Imperfect elimination of the base metals whilst on the 
cupel isa frequent cause of high results. This is especially 
the case where the lead buttons contain copper. . The only 
safe plan is to have lead buttons which are perfectly soft and 
free from copper, and in each case to push the cupel back into 
a hot part of the muffle just before the button brightens, and 
thus brighten at a high temperature. 

Another source of error in gold assays is loss of gold in 
parting, and imperfect elimination of silver from the gold in 
parting. The first source of error is always due to careless 
manipulation; the second is due to carelessness in parting. In 
order to insure the solution of the silver the gold-silver bead 
should contain at least three and a half parts of silver to each 
part of gold present. The buttons should invariably be parted 
in acids of two different strengths. The method adopted by 
the author is to part in nitric acid of 13° Baumé until all action 
of the acid has apparently ceased; pour off this acid, and boil 
in nitric acid of 32° Baumé for four minutes. 

The size of the lead button also has an influence on the 
loss in cupellation. An excessively large button will cause an 
excessive loss. A button weighing from 7 to 8 grammes is the 
size preferred by the writer for ores containing up to 300 
ounces of silver and 5 ounces of gold per ton. Such a button 
is sufficiently large to collect all the precious metals, and pre- 
sents the advantage that it is on the cupel but a short time. 

The weight and quality of the cupel used also have an in- 
fluence on the loss in cupellation. The cupel should weigh at 
least twice as much as the button to be cupelled; it should be 
quite hard and made of fine bone-ash. If too soft, or made of 
coarse bone-ash, the cupel absorption will be increased. . If too 
hard the cupel will not readily absorb the litharge formed. 
The cupel preferred by the author is made of XX bone-ash 
and tamped sufficiently so that when thoroughly dry it will 
not break when dropped from a height of two feet. 


388 APPENDIX C: 


The temperature during fusion or scorification and the 
character of the slag also have an influence on the losses by 
slag absorption. The fusions should be started at a compara- 
tively low temperature which should be gradually raised to a 
bright red at the finish. The fluxes added should be so pro- 
portioned that the slag will be perfectly fluid, pouring clean 
and thus allowing of a perfect separation of the slag and 
button. As it is essential that the charge be equally heated 
throughout, so that no portion commences to fuse before 
another, and that the temperature be under control, the 
Colorado practice of performing the fusions in the muffle is to 
be recommended. The essential conditions can be more 
readily attained in the muffle than in the wind-furnace. 

The following table gives the results of Messrs. Mason and 
Bowman’s experiments to determine the losses in cupellation 
under conditions such as would prevail in careful commercial 


work: 


TABLE I.—LOSSES OF GOLD AND SILVER IN CUPELLATION. 


Wt. Silver 


Wt. Gold 


Wt. Silver 





Wt. Gold 





- Silver 


f aft Silver Gold Loss 
Choe Ge eciite: Capeling. Cupellice! Loss.) | Coe pee Per Cent. 
210.765 | 338.030 | 206.360 | 335.025 4.405 3.005 2.09 0.888 
543.165 | 349.020 | 535.645 | 348.200 7.520 0.820 1.38 0.234 
206.360 | 335.025 | 200.325 | 334.365 6.035 0.660 2.92 0.197 
535.645 | 348.200 | 523.330 | 346.900 | 12.315 1.300 2.29 0.373 
200.325 | 334.365 | 196.720 | 333.120 3.905 1.245 1.79 0.372 
523.330 | 346.900 | 514.765 | 345.790 8.565 I.110 1.63 0.319 
196.720 | 332.575 | 191.733 | 331.725 | 4.987 0.850 2.53 0.255 
514.765 | 345.790 | 503.950 | 344.150 | 10.815 1.640 2.10 0.474 
191.7343 | 331.725 | 187.820 | 330.600 3.013 1.125 2.03 0.338 
434.180 | 344.965 | 424.925 | 344.265 9.255 0.700 2513 0.202 
187.820 | 330.600 | 184.525 | 329.900 3.295 0.700 1.80 0.211 
424.925 | 334.650 | 419.975 | 333.960 4.050 0.690 0.95 0.206 
184.525 | 329.900 | 180.560 | 329.130 3.965 0.770 2.14 0.233 
419.975 | 220.635 | 410.430 | 220.200 9.545 0.435 2.24 0.197 
410.430 | 329.130 | 403.365 | 328.860 7.075 0.270 iv72 0.082 
403.365 | 220.200 | 394.550 | 219.835 8.815 0.365 2:19 0.165 





Average silver loss.... 





I.99 per cent. 


Average gold loss... .0.296 per cent. 


APPENDIX C. 389 


The following table gives the results of some experiments 
undertaken by the author to determine the losses under 
various conditions: 


TABLE II.—LOSS OF GOLD IN CUPELLATION, 














Parts Ag 
Parts Parts Grms.| and Au Parts Au Loss Au | Loss Ag 
Noe) reat | atyet (adet) citteha. | paitety, (Pats 4#-Wper Cent. [Per Coat 
tion. 
Al | 799.8 7 795-4 . 0.55 
2 799.8 eee 7 795-0 . 0.60 
3 799.8 fa is 795.0 . 0.60 
4 800.3 ° e i 794.8 e ° O. 69 
5 799.9 snr 7 795.7 0.52 
6 | 799.9 tees A 798.0 : 0.23 
BI 200.7 4 194.4 | 3.14 
2 200.8 F 4 194.6 3.09 
3 200.6 4 195.3 2.64 
4} 200.4 . = 197.3 1.55 
5 200.4 4 199.1 0.65 
OP 200.1 : 8 192.4 siatSnp Petes 3.85 
2 200.0 : 8 IQI.4 aeetets eves 4.30 
2 200.1 8 193.7 sew Gata 3.20 
4 200.0 8 196.2 . ° 1.90 
5 200.6 Ceotacs 8 199.4 ac 0.60 
Dr 800.0 200.2 7 987.7 ; r23 iy 
2| 799.8 199.7 7 987.7 : 1.18 oss 
21 499.8 199.6 7 989.0 esi et 1.04 | 4g a 
4 799.8 200.0 + 989 0 setae oie ai 1.08 cent, 
5 799.9 199.7 9) 994.2 eeteees ne 0.52 
EI 200. 2 1000.6 7 1173.6 200.2 973.4 0.00 2.75 
2{ 200.1 1000.8 7G deh 200.4 O7771h| 0.15 2.34 
Sel ea200.7 IOOI.2 a 1185.4 201.4 984.0) *0.35 1.65 
4 | 200.0 IOOI.4 7 1190.9 200.0 990.9 | 0.00 1.05 
Fr 100.35 1000.0 yi Setar 100.35 aie 0.00 
2 100.35 1000.0 ” 100. 25 eee 0.09 
3 100.9 1000.0 7 100.45 ar i 0.44 
4 | 100.4 1000.0 7 100.25 whatets 0.15 
GI 101.9 1000.0 Be 101.7 ines 0.19 
ST 102.2 1000.0 z sees 102.4 ates atl? =O. 20 
3 IOI.5 1000.0 7 rae IOI.1 ree 0.39 
Keive 102.0 1000.0 7 Sesge 102.2 Sod hee 
H1 100.6 1000.0 7 sae 99.3 ite 1.29 
2 100.0 1000.0 7 ones 99.8 nietsie 0.20 
0) 100.1 1000.0 7 cece 100.8 pert fi 0,00 
4 100.3 1000.0 7 ree bre 100.5 Sop. al were 
5 | 100.0 1000.0 7 ete = 100.9 cemei a ie 0.90 





Average loss Au per cent, 0.86. * Indicates a gain in place of loss. 


390 APPENDIX. C, 


REMARKS. 


A. No. 1 was cupelled at the back of the muffle, the others 
being placed in order up to No. 6, which was at the front. 
The temperature was lower than is usually employed. 

B. No. 1 run at the rear and No. 5 in front of the muffle. 
The temperature was higher than in A. 

C. The conditions were the same as in B. 

D. The conditions were the same as in A. 

E. The conditions were the same as in B. In parting but 
one acid (sp. gr. I.15) was used. 

F. No. 1 at the rear and No. 4 in the front of the muffle. 
The temperature was higher than is usual in commercial work, 
The parting was performed in two acids of ..07 and 1.27 sp. 
er. respectively. 

G. The conditions were the same as in F, except that the 
first acid was 1.20 and the second acid 1.27 sp. gr. 

H. The conditions were the same as in F, except that in 
parting but one acid (sp. gr. 1.15) was used. 

Table III gives the results of some experiments made by 
the author to determine the losses under various conditions 
and where larger amounts of lead were present. Each part is 
0.5 milligramme. _ 

REMARKS. 


A. No 1 was cupelled in the front and No. 2 in the middle 
of a hot muffle. 

B. Nos. 1 and 2 inthe front and Nos. 3 and 4 in the middle; 
300 parts of copper were added. 

C. No. 1 in front and No. 2 in the middle; 600 parts of 
copper were added. 

D. Nos. 1 and:2 in front and No, 3) inethe middle: 600 
parts of zinc were added. 

E. Nos. 1 and 2 in front and Nos. 3 and 4 in the middle; 
350 parts of zinc and 300 parts of antimony were added. 

F. No. 1 in front and No. 2 in the middle; 200 parts of 
copper, 250 parts of zinc, 200 parts of antimony, and 200 parts 
of iron sulphide were added. 


APPENDIX C. 391 


TABLE III.—LOSSES OF GOLD AND SILVER IN CUPELLATION. 





Parts Ag 
Parts Parts {Grammes| and Au_ | Parts Au pie Loss Hoe 
No. | Au Ag Pb after after ~ A Au & 
Taken.| Taken. Taken. | Cupella- | Parting. 8. Per Cent. Aga 
tion, ent 
4.0 300.6 14.5 295.8 3.4 292.4 2.55 2.67 
Bit 15755 301.0 14.5 282.6 3.4 270.2 4.25 7.24 
ints a GEG es 300.6 14.4 296.5 3.3 293.2 5-71 2.46 
ae SO 300.7 14.4 296.9 2.9 294.0 2433 2.23 
se ae Pe 300.2 14.4 280.6 3.4 B7T7ie 8.11 7.66 
4 | 3.45 300.3 14.4 281.6 3.05 278.5 11.59 7.26 
C1}. 4.3 300.5 14.2 297.8 Ase 293.6 2:32 2523 
21) 4.0 300.4 14.2 278.8 4.0 274.8 2.50 8.52 
Dir} 3.8 300.7 14.2 290.1 3.5 286.6 7.90 4.68 
2a 5.7 300.0 14.2 288.5 3.4 285.1 8.10 4.96 
1/5325 300.5 14.2 271.0 3.35 267.6 4.30 10.94 
Bini. 3:6 300.0 14. 287.6 ar4 284.3 8.33 5.2 
Bt 33.50 300.0 14. 288.1 27 285.4 10.00 4.87 
3 | 4.2 300. 2 14. 275.7 3.8 271.9 9.52 9.43 
AU 252 300.6 Tq. 270.2 2:0 267.4 12.81 TA037 
Ea {4:2 300.0 14. 291.4 3.9 287.5 7.14 PEGE | 
Ca Ae? 301.8 14. 279.5 4.1 275.4 253% 8.74 
Gat 8:7 331.0 14.5 334.8 8.65 320.15 0.57 1:46" 
2 | 5-15 | 340.8 14.5 340.6 5.05 335-55 1.94 1.54* 
ey 326.9 14.5 326.8 5.00 321.8 1.96 1.50% 
4] 5.5 334-7 14.5 334-7 5-40 329.3 1.82 1.61* 
JL) 3-4 317.1 14.5 314.4 5:37 311.03 0.90 1.92” 
oe Me 332.65 14.5 327.2 3756 323.64 ie 2.71% 
Kr | 4.8 33254 14.4 326.0 4.65 321.35 83 3.32 
21 4.4 349.6 14.4 339-8 4.2 335.6 4.54 4.00 
Lt 1 93:9 314.6 14.4 308.9 27 305.2 ae 2.98 
2) 3-7 315.8 14.4 311.4 3-5 397.9 5-40 2.50 
MI {| 3.95 302.0 14.2 290.9 3.72 286.18 5.82 5.23 
2013.2 306.9 14.2 296.3 3.00 293-3 6.25 4.43 
Nr | 3.6 300.0 14. 292.4 3.55 288.85 1:30 3.71 
2hi8 3 312.0 14. 306.9 3.25 303.65 1.51 2.68 


In all of the above cases the buttons were cupelled at too 
high a temperature to show feather-litharge on the cupel. 

In the following experiments the cupellations were all per- 
formed inthe front of the furnace and all the cupels showed 
litharge crystals. 

G.* The gold and silver were wrapped in pure lead and 
cupelled cold. The average loss in silver was 1.54 per cent. 
and in gold 1.32 per cent. These results agree closely with a 
number of results previously obtained by the author in the 


302 APPENDIX C. 


cupellation of base bullion from silver-lead blast-furnace 
smelting. 

In the following experiments the charges were scorified 
previous to cupellation, the buttons after scorification weighing 
from 5 to6grammes. The results confirm the author’s pre- 
vious experience in operating on base bullion, there being no 
advantage in previous scorification except in the case of ex- 
tremely base bullion. Even in the case of quite impure bull- 
ion, provided the cupellations are started ot and as soon as 
the lead begins to drive well, if the cupels are moved forward 
so that the cupellations are continued cold the results will be 
quite as high as where previous cupellation is adopted. 

J. 14.5 grammes of pure lead were used. 

K. 300 parts of copper were added. 

L. 400 parts of zinc were added. 

M. 300 parts of zinc and 300 parts of copper were added. 

N. 300 parts of zinc, 250 parts of copper, 300 parts of anti- 
mony, and 350 parts of iron sulphide were added. 

Table IV gives the results of Messrs. Mason and Bowman’s 
experiments to determine the losses in scorification and cupel- 
lation. 

In Table I we found the loss of silver in cupellation to be 
1.99 per cent., and the loss in gold in cupellation to be 0.296 
per cent. Deducting these percentages from the above aver- 
ages (Table IV), we have for the losses in scorification: Silver 
0.55 per cent., and gold 0.574 per cent. 

Table V gives the results of Mr. Henry E. Wood, assayer, 
Denver, Colo., on the assay of silver sulphides by scorification 
and cupellation. In these experiments the slags and cupels 
were saved, and the absorbed silver subsequently determined. 
They do not show the silver lost by volatilization. 

Table VI (Frederic P. Dewey) gives the results on 
eleven lots of regular Russell process sulphides assayed as 
follows: Weigh out »!5 A. T. of sulphides, 55 gms. of test-lead, 
and 2 or 3 gms. of borax-glass. One half of the test-lead is 
placed in the bottom of the scorifier and hollowed out; the 
sulphides are put into the hollow and the balance of the test- 


APPENDIX AC, 


AND CUPELLATION. 


543.105 








393 


TABLE IV.—LOSSES OF GOLD AND SILVER IN SCORIFICATION 





Wt. Silver Wt. Gold Wt. Silver Wt. Gold Silver | Gold 
before Scori- | before Scori-| after Scori- | after Scori- Silver Gold Loss, | Loss 
fying and fying and fying and fying and Loss oss Per’ Per 
Cupelling. upelling. Cupelling. Cupelling. Cent. | Cent 
466.850 357.750 453.200 351.982 ¥3,60507)55-708 | 2:922|' 161 
480.052 388.525 469.575 382.565 TOMA 7 75). 5-GOO 49225891) 1553 
455.000 353-782 434.365 346.234 | 20.635 | 7.548 | 4.53 | 2.10 
471.375 384.365 456.475 382.033 14.900 | 2.332 | 3 16 | 0.60 
436.165 348.034 425.780 346.325 10.385 | 1.709 | 2 38 | 0.49 
458.275 383.833 448.818 381.875 9.457 | 1.958 | 2.06 | 0.51 
427.580 348.125 418.533 346.435 9.057 | 1.690 | 2.11 | 0 48 
652.350 478.120 641.520 471.920 10.830 | 6.200 | 1.66 | I.29 
354.200 348.235 344.520 346.250 9.680 71 -1:985 | 2.°732|).0.57 
643.320 473.720 628.175 471.225 15.155 | 2.495 | 2.35 | 0.52 
346.320 348.050 340.500 346.465 5.820 | 1.585 | 1.68 | 0.45 
614.920 356.425 600.565 352.435 T4355 We 3-900) 2135 fell 
342.300 348.265 333-075 345.535 9.225 | 2.730 | 2.69 | 0.78 
602.365 354.235 592.200 352.525 10.165 | 1.710 | 1.68 | 0.48 
334-875 347-335 327.140 345.800 7-735 | 1.535 | 2.30 |.0.44 
594.COO 354.325 581.465 352.075 12,535 12.250] 2,11 | 0.63 
328.840 347.600 317.830 344.135 EL. BLO" W'9°465103.37-1 0.99 
567.620 353-875 555.365 350.925 | 12.535 | 2.950 | 2.15 | 0.83 
219.450 221.635 210.765 219.250 8.655" | 2.3851 3.95 | 1.07 
557.105 352.725 349.020 E4000 3.705 12.51. 1-91.05 


Average silver loss.... 2.54 per cent. Average gold loss.... 0.87 per cent. 


lead poured over them; the borax is then placed ontop. The 
assay is then conducted in the usual manner, the slags and 
cupels being saved, ground up, and assayed, the result being 
added to the regular assay. 

Table VII gives the results of a number of experiments 
undertaken by the author to determine the loss of silver in the 
assay of rich silver sulphides, and also to see if some method 
other than the foregoing might not be adopted to advantage. 

A few ounces of silver sulphide were prepared by dissolv- 
ing quite pure silver chloride in sodium hyposulphite and pre- 
cipitating the silver as a sulphide by the addition of sodium 
sulphide to the solution. After filtration and slight washing, 
the precipitate was dried, ground, and thoroughly mixed; and 
the percentage of silver was then determined by carefully 


394 APPENDIX. 


TABLE V.—LOSSES IN THE SCORIFICATION-ASSAY OF SILVER 


SULPHIDES. 

Ounces of Silver Per Cent. Silver Recovered 
per Ton of Average of from 
Sulphides. Slag and Cupel. 

Under 500 1 lot 4.170 

500 to 1,000 6 lots 2.910 

I,000 tO 1,500 14 lots 2.996 
I,500 to 2,000 g lots 2.540 
2,000 to 2,500 12 lots 2.109 
2,509 to 3,000 21 lots 1.867 
3,000 to 3,500 Ig lots 1.860 
3,500 to 4,000 1g lots 1.821 
4,000 to 4,500 to lots 1.695 
4,500 to 5,000 7 lots I.700 
5,000 to 5,500 4 lots 1.845 
5,500 to 6,000 4 lots 1.895 
6,000 to 6,500 1 lot 1.630 
6,500 to 7,000 4 lots 777 
7,000 to 7,500 2 lots 1.640 
7,500 to 8,000 I lot 1.420 
8,000 to 8,500 3 lots 1.537 
g,000 to 9,500 3 lots 1.460 
10,500 to 11,000 I lot 1.570 
II,500 to 12,000 I\lot 1.340 
12,000 to 12,500 I lot 1.270 

x lot 1.260 


17,000 to 17,500 





weighing out several portions of 0.05 A. T.* each on the assay- 
balance used for weighing the silver buttons resulting from 
assays; dissolving each portion in nitric acid of 27° Baumé; 
boiling to expel the red fumes; diluting with distilled water to 
200 cc., and titrating with a standard solution of potassium 
sulphocyanate; adding about I cc. of a strong solution of 
ammonium ferric alum as an indicator (Volhard’s method). 
This method was adopted because the Gay-Lussac titration 
with standard salt solution could not be used on account of 
the sulphur set free during solution and the consequent cloudi- 
ness of the solution. This free sulphur would also have inter- 
fered with the gravimetric determination (precipitating the 


* The resulis have been reduced to ounces pe> ton, rather than percent- 
ages, for the sake otf uniformitv and convenience. One ounce per ton is 
0.00343 per cent. 


APPENDIX C. 395. 


TABLE V1.—LOSSES IN THE SCORIFICATION-ASSAY OF SILVER 
SULPHIDES, 





Oz. per Ton by 


Oz. per Ton Per Cent. 
Commercial i i 


Total Oz. per 
Total Oz. per Ton. Ton P 


in in 
Assay. Slag and Cupel. |Slag and Cupel. 


1st Assayer, ist Assayer. rst Assayer. att fase teat 2d Assayer. 
8,675.20 144.11 1.622 8,819.31 8,782 
10,074.25 189 35 1.844 10,263 60 10,119 
10, 783.35 189.00 1.720 10,972.35 10,938 
10,902.30 194.38 1.752 11,096.68 bi220 
11,015.73 Ig1.609 1.710 LE;207242 II,0gO 
11,238.40 175.22 1.535 11,413.62 11,548 
11,828.75 176.72 TAzt 12,005.47 12,046 
12,566.55 199.21 1,560 12,765.76 12,821 
12,665.85 199.87 1.553 12,855.72 12,841 
13,001.65 229.84 bir het 13,231.49 13,187 
13,625 50 226.52 1.635 13,852.02 13,919 





silver as a chloride and weighing it as such). Volhard’s 
method, provided copper is absent, gives very correct results, 
and has been used by the writer for years with entire satisfac- 
tion. The average silver-contents of the sulphides, as thus 
shown by several closely-agreeing determinations, was 19,693 
ounces per ton of 2000 pounds. 

The silver was next determined by the combination method 
described in Part III, Chapter IV, page 250. The result of 
two determinations was 19,590 and 19,625 ounces per ton; 
average, 19,608; average per cent. of the silver present thus 
found, 99.56. 

_ Table VII gives the results of the different determinations 
by both scorification- and crucible-assay. 

Remarks on the Scorification-Assays.—The assays were run 
in the usual manner, from 30 to 40 grammes of test-lead and 
from 0.5 to I gramme of borax-glass being used. In addition 
to the regular fluxes, there were added the following reagents: 

Momieearanimes ; 0.5 of Sb.O;,"0.5 of As.O. and 0.5 of Cu: 
The button, after cupellation, weighed 19,764 milligrammes ; 
but, as it showed the presence of copper, it was recupelled with 
I gramme of lead, and the weight of this second button is the 
result reported in the table. 


390 APPENDIX C. 


TABLE VII.—COMPARISON OF SCORIFICATION- AND CRUCIBLE- 
ASSAYS. 





SCORIFICATION METHOD. CrucisLE METHOD. 


Result 
Amount Result 
No. Amount Sul- Ounces Per cent. No. Sulphides}| Ounces Per cent. 




















phides Taken. per Ton Che Taken. | per Ton. Bee 
Grammes, 
: iar esr 0,05 AL 1. 19,576 | 99.41 Toth ouion 0.5 19,556 | 99.20 
M2 a ewe aiss 0.05 i. 19,714 |100. II RPh Asa 0.5 19,446 | 98.74 
ase ee et OcO Sut ole 19,562:1° 00.3 35|) Sone wees 05 19,501 | 99.02 
Fy See Os5e ters 105573 \ O0cdQalt Aare s seals 0.25 19,200 ; 97-49 
Birists, ches O;O8 ayes 19,075: 1°00. 01a Sere apis 0.5 18.734 |- 05.13 
“8 Pacino 0.5 gramme..| 16)547:1),00.25 10 ass. e a 0.5 19,396 | 98.49 
ated ee ae O'5 i 10,400: 108.554, A fires ates 0.5 19,416 | 98.59 
Ds salven. 0.5 ee 19,012 -)' G9. 580) Sec. ee ee 19,5060 | 99.05 
PANELAZE | sciere ste e sates wre 19,583 |°99.44 || Averages|\.. 9 ease 19,344 | 98.22 





No. 2. The charge was the same as in No. 1. The button 
weighed 19,841 milligrammes, and was dissolved in nitric acid, 
the solution showing the presence of copper. ‘The result, as 
reported in the table, was obtained by titration of the solution 
from the button with standard sulphocyanate solution, which 
method would necessarily give a high result, owing to the 
presence of copper. 

No. 3. This was run without the addition of fluxes other 
than the regular charge of test-lead and borax. 

No. 4. Same as No. 3. 

No. 5. Added grammes: BaSO,, 0.5; Sb,O,, 0.5 ; FeS, 04; 
G0.5,.and'7.n, 0.5; 

No. 6. Added 0.5 gramme of Cu. 

No. 7. Added 0.5 gramme of Zn. 

No. 8. Added 0.5 gramme of Fc. ; 

Remarks on the Crucible-Assays.—The fusions were run in 
10-gramme Denver crucibles, the fusion being performed in the 
muffle-furnace. The regular charges of litharge, sodium bi- 
carbonate, borax-glass, lead-flux, and nails were added. The 
time of fusion was about thirty minutes in each case. In 


APPENDIX C. 307 


addition to the regular fluxes there were added the following 
reagents: 


Domeercded o,5 At Ll. of pure SiO,. 

Nom2erxoaccu crammes ; oi10,, 5; ob,O,, 1; As,O,, 1; Cu, 
Weantoe 1. 
menaced O56 A. 1. of pure S10,. 


No. 3 

No.4. Lhe same as No. 3. 

No. 5. Added grammes: SiO,, 5; BaSO,, 5; Fe,O,, 5. 

No. 6. Added 14 grammes of pure SiO,,. 

eee ccded erammes: S10,, 5; Zn, 1; S, 1, and Cu, 0.5. 
No. 8. Added grammes: SiO,, 5; BaSO}, 5, and Fe,O,, 5. 


In all the assays the same precautions were adopted as 
would ordinarily be observed in careful commercial work. 

The crucible-assays were made, not because this was con- 
sidered the proper method for the assay of high-grade silver 
sulphides, but in order to obtain comparative results by this 
and the scorification method. 

The following table gives the results of a few experiments 
undertaken by the author to determine the loss of gold and 
silver in the crucible-assay of ores. Whilst the results show 
too great a variation for any averages to be derived from 
them, they tend to show that the crucible-assay for gold is more 
accurate than is generally supposed. The average loss in 
silver (2.58 per cent.) in these experiments is quite close to 
that found by Mason and Bowman in the scorification-assay 
(2.54 per cent.). 


REMARKS. 


A. 4A. T. of pure SiO, was added. 

B. 10 grammes of SiO, and 5 grammes of ZnO were 
added. 

C. 4A. T. SiO, added. The button was not weighed prior 
to parting. 

D. 4A. T. of SiO, was added. No silver was added to 
this assay. : 


398 APPENDIX C. 


TABLE VIII.—LOSSES OF GOLD AND SILVER IN CRUCIBLE-ASSAY. 


Parts Au | Parts A vad Ag | Parts Au Loss Au | Loss A 

No. T faa Takeqt after. ies ae Parts Ag. Per cent. Ber tenn 

Cupellation. 8: - 

AI 4.7 216.3 215.6 4-65 210.95 1.06 2.47 
2 4.0 205.5 206.5 4.0 202.5 0.00 1.93 
BI 4.0 208.0 208.7 4.0 204.7 0.00 1.58 
2 3.6 277.0 217-2 3.6 213.6 0.00 1.84 
G 202.5 ZOO0, = | Vee stator 202.6 Pet pe 0.04 etehs 
D POO LO LOW sero a 200.3 steje See Pai a. 28 ata 
Er 24.25 306.0 321.0 24.23 296.77 0.08 3501 
2 24.6 317.5 330.1 24.5 305.6 0.40 3-74 
Tek 26.4 a2 ORF 340.4 26.4 314.0 0.00 2.08 
2 2273 308.9 324.0 22.5 300.7 0.00 2.65 
G 1308 226.8 225.3 1335 222.0 0.74 2.1% 
Hr 14.5 215 2 22525 14.5 2Ttas 0.00 1.81 
2 rhs 214.9 223.0 15.2 207.8 0.65 3.30 
K 144 232.0 235.4 14.25 221.15 1.04 4.66 
Average..|...0.30 2.58 





E. 5 grammes of SiO,, 5 grammes of BaSO, and 5 grammes 
of FeS were added. 

F. 10 grammes of FeS, 3 grammes of ZnO and 2 grammes 
of Cu were added. 

G. 7.5 grammes of SiO, and 5 grammes of BaSO, were 
added. 

H. 5 grammes of SiO,, 5 grammes of BaSO, and 5 grammes 
of CaO were added. 

K. 7.5 grammes of SiO, and 7 grammes of FeS were added. 

To the above charges there were added the proper fluxes 
to produce a fluid slag and a lead button of from 7 to i2 
grammes in weight. The cupellations were performed so as 
to show “ feather-litharge”’ on the cupels in each case. ‘Lhe 
parting was done in two acids of I.15 sp. gr. and 1.27 sp. gi. 
respectively. 

In connection with Table VIII the following results re 
cently obtained by the author on some samples of Cripple 
creek telluride ores will be of interest. The gold was deter- 
mined independently by an eminent chemist by wet analysis 
The fire-assays were made by the author: 


= 


APPENDIX C. 399 


TABLE IX.—COMPARISON OF WET AND FIRE ASSAYS FOR GOLD. 


Oz. Au Oz. Au Oz. Au by 
Tee by Wet by Crucible Scorification 
Method. Method. Method. 








For the scorification-assays 31, A. T. of the ore was taken 
in the case of samples Nos. 1 and 3. In the case of No. 2 74 
A. T. was taken. The charge in each case was: test-lead, 4c 
grammes; litharge, 10 grammes, and borax-glass, 0.5 grammes. 
The ore was mixed with one half of the test-lead. The lith- 
arge was then added as a cover, and on top of this was placed 
the remainder of the test-lead and the borax. 


For the crucible-assays the following charge was used: 


SONS BS aie Av BCI Ie iN Ee ne go A. T. 
SITES. o.. 5 o's's s Reeser cb te atte niece 50 grammes 
Pee IGet teen terraces sale Vere aie’ © dae; 0/0 6 : 
PO ROLCAL UAT a tales ieie tle alta vet wal acon 5 s 
Parr me IASG Ue w scyss ss aw 09 C0013 9,0 #100 3 4 
aa tlpee eda crss sects < «10s 3 a.vads 0's Painke one: 


Whilst this table would seem to conflict with those preced- 
ing it, which have shown that there is a considerable loss of 
gold in fusion, etc., it must be remembered that there is also 
always some silver left with the gold after parting. Where 
the parting is properly performed this gain will frequently 
nearly equal the loss of gold in the previous operations. A 
recent analysis of a quantity of gold resulting from careful 
parting showed it to contain 0.3 per cent. of silver. An analy- 
sis of some gold resulting from parting where only one dilute 
acid had been used showed it to contain 1.15 per cent. of 
silver. 


400 APPENDIX C. 


The following table gives the results of a number of expert- 
ments made by T. K. Rose* to determine the loss of gold in 
the assay of gold bullion. 


TABLE X.—LOSS OF GOLD IN THE ASSAY OF GOLD BULLION. 


Standard of Alloy. meremeisthe nis M08 Oar Gola 
916.6 +0.250 0.63 
g00.0 +0.225 0.65 
800.0 —0.075 1.00 
666.6 ——O.2 1.20 
546 =O) —O, if 220 
333-3 —2.8 2: 0y, 


Prof. Roberts-Austent found the loss of gold to be 0.723 
at the ordinary temperature, and 0.645 at a slightly lower 
temperature than is usual in gold bullion assaying, using Brit- 
ish standard gold (916.6 parts gold and 83.4 parts copper). 


* The Metallurgy of Gold. T. Kirke Rose. London, 1894 
t Percy’s Metallurgy of Silver and Gold, p. 275. 


APPENDIX D. 


LABORATORY TESTS IN CONNECTION WITH THE 
Pee LION OF GOLD FROM ORES BY. THE 
yew tL =PROCESS. 


As the cyanide method for the extraction of gold from 
ores is extensively used in the United States and elsewhere, 
and appears destined to prove a factor of increasing impor- 
tance in the metallurgy of gold, a description of the latest 
laboratory methods may prove of interest. 

The history of the development of the process in the 
United States has been analogous to that of all new processes. 
Many failures are to be recorded and a few successes. It is 
the opinion of the writer that, had the following simple tests 
been better understood, many of the failures would not have 
occurred, and we should probably have a larger number of 
successful plants in operation. While the process is not 
simple, but requires a high degree of chemical and engineer- 
ing skill, the determination of the adaptability of an ore to 
the method is generally not difficult. While the laboratory 
results will not always coincide with the actual results 
obtained in the mill, they will serve as a guide and control on 
the working of the mill, and will generally suffice to determine 
if the ore can be economically treated by the process. Objec- 
tion may reasonably be made that in small tests conditions 
different from those which occur on a larger scale are intro- 
duced. However, tests made on from 25 to 100 pounds of 
ore should be closely duplicated in the mill. Tests on a 

401 


402 APPENDIX DP. 


smaller scale will serve to show what may be expected in the 
mill. 

In determining the adaptability of an ore to this method 
of treatment, and the percentage of extraction which may 
be expected in the mill, the following must receive considera- 
tion: 

The percentage of extraction will generally be somewhat 
higher in the laboratory than in the mill, but the consumption 
of cyanide will also be higher in the laboratory. 

A most important point is the character of the ore, par- 
ticularly the manner in which the gold is contained in it; 
whether it is in the free state; coarse or fine; intimately 
associated with pyrites or other sulphides; the character of 
the sulphides with which it is associated; whether it is com- 
bined or alloyed with bismuth, tellurium, or other elements. 
An examination by the eye, with or without the aid of a mag- 
nifying-glass, will frequently settle these points. Should the 
sample be in a finely pulverized condition, ‘careful vanning 
may be resorted to with advantage. 

The size to which it is advantageous to crush the ore will 
depend largely upon the character of the ore and its gangue. 
Should the gold be unevenly disseminated throughout the 
material, and the gangue be hard and non-porous, fine crush- 
ing is essential to a good extraction. The Cripple Creek ores 
are examples of such material, crushing to 40-mesh, or finer, 
being necessary to insure a good extraction of the gold. 
Some ores, however, being very porous, readily permit the 
solutions to percolate, and consequently can be successfully 
leached in a coarse condition. The Mercur ores are examples 
of such material, pieces one-half inch or more in diamete~ 
being successfully leached. 

Whether the ore requires roasting prior to leack:ny will 
depend principally upon the condition of the gold in it. If 
present as a telluride, the gold may be extracted from the 
raw ore by fine grinding and leaching with potassium cyanide; 
but the action of the solution on the tellurides is slow, and it 
may be more economical to subject the ore to a preliminary 


APPENDIX D. 403 


roast. Roasting presents two disadvantages; it materially 
increases the cost of treatment, and it is liable to result in 
the formation of salts detrimental to the subsequent leaching; 
for example, soluble sulphates, which decompose potassium 
cyanide. Unless the roasting is carefully conducted, gold 
may be lost by volatilization. This is especially the case with 
tellurides. On the other hand, many ores are rendered more 
porous by roasting, and thus the rate of percolation is in- 
creased and coarser particles can be leached. 

The best strength of solution and the time of maceration 
and percolation are important points. The time required and 
the amount of cyanide consumed will depend largely upon the 
strength of the solution employed. For example, the time 
required with a I per cent solution will generally be much less 
than with an 0.25 per cent solution. On the other hand, for 
many ores the consumption of cyanide with a1 per cent solu- 
tion is so great that the process becomes commercially im- 
practicable, while with dilute solutions the ore may possibly 
be treated with success. In this connection mention may be 
made of the use of additional reagents, such as sodium per- 
oxide, bromine, etc., which ave sazd to facilitate the extraction 
12 many cases. This is a mooted point, and the use of these 
reagents is objected to by some, as they have a tendency to 
increase largely the consumption of zinc, when zinc is the 
precipitant employed, and to foul the solution. According 
to the equation of Elsner, 


4Au + 8KCN + O, + 2H,O = 4KAu(CN), + 2KOH, 


oxygen, or an oxidizer, is essential to the solution of the gold. 
It would appear to the writer that the necessary oxygen can 
be obtained from the air at less cost, and quite as conveniently, 
as by the introduction of expensive reagents. 

The amount of potassium cyanide required per ton of ore, 
including the amount which is destroyed during treatment, is 
a vital point. The character of the ore and its associated 
minerals will determine the consumption of cyanide. 

The rate of percolation of the solution through the ore is 


404 APPENDIX D. 


a question of some importance. It would appear as if too 
much had been made of this point, as it is essential that the 
solution should remain in contact with the ore for a consider- 
able time in order to insure a good extraction. On most 
ores the percolation will generally be quite as rapid as the 
necessary time of contact will permit. 

A small quantity of the ore should be ground to 30-mesh, 
which is a suitable degree of fineness for the preliminary 
experiments. A sample is carefully cut out of this prepared 
pulp, ground to pass 100-mesh, and assayed for gold and 
silver in the usual manner. 

A quantity of stock solution, containing 0.5 or 0.6 per 
cent of potassium cyanide, should be prepared. As this so- 
lution is lable to decomposition, it should be kept in a 
stoppered bottle, protected from the air and sunlight, and 
should be tested from time to time according to Test 6. 

It is necessary that the water used in making up the stock 
solution should be quite pure. It should always be tested for 
impurities, for should it contain iron salts, magnesium sul- 
phate, salts with an acid reaction, soluble sulphides, free 
carbonic acid, or sulphuric acid, they will decompose the 
potassium cyanide. 

1. Determination of Acidity.—Should an ore be acid, the 
result will be decomposition of potassium cyanide unless this 
acidity is destroyed before the cyanide solution is added. 

Soluble Acidity.—Agitate 10 grammes of the pulp for Io 
minutes with 50 cc. of water; filter, and test the filtrate with — 
litmus-paper for acidity. Should acidity be shown, wash the 
ore until the washings no longer give an acid reaction when 
tested with litmus-paper. Now titrate the total filtrate with 
decinormal caustic-soda solution, until the neutral point is . 
obtained, using litmus as an indicator. 

Latent Acidity.—Transfer the washed ore to a small por- 
celain evaporating-dish; cover with water; add a measured 
excess of decinormal caustic-soda solution; stirand titrate the 
excess of soda with decinormal-acid solution. This gives the 
latent acidity. 


APPENDIX D. 405 


Total Acidity.—The sum of the above tests gives the total 
acidity; but as this is frequently all that is required, it may 
- be determined as follows: Introduce Io grammes of the pulp 
into a stoppered bottle with some water; add a measured 
excess of the caustic-soda solution, agitate for 20 minutes, and 
then titrate back with decinormal-acid solution. 

The soluble acidity is due to salts with an acid reaction, 
such as ferrous sulphate, zinc sulphate, copper sulphate, etc., 
or to free sulphuric acid from the decomposition of pyrites, 
tellurous acid, etc. It may be overcome by giving the ore a 
preliminary wash with water. This washing is followed by 
treatinent with a weak solution of caustic soda or caustic lime, 
which neutralizes the latent acidity due to basic salts. The 
amount of alkali necessary is determined from the quantity 
of decinormal-soda solution used in the above experiments. 
Unless the ore contains a large amount of free acid, the pre- 
liminary washing with water may be omitted; the total acidity 
being determined and reported in terms of lime. Sufficient 
lime is then added to the ore, before crushing, so that it 
becomes thoroughly incorporated before the ore reaches the 
tanks, and when the tank is charged, the SLICE solution is 
at once admitted. 

2. Test for the Consumption of Cyanide——The original 
strength of the stock solution being known, it is only neces- 
sary to determine its strength after it has been used on a lot 
of ore, to arrive at the consumption. 

Introduce 20 grammes of ore (treated with a sufficient 
quantity of soda or lime, if necessary) into a glass-stoppered 
bottle; add 40 cc. of the cyanide solution, and agitate for 20 
minutes; filter; measure off 20 cc. of the filtrate and deter- 
mine the amount of undecomposed potassium cyanide remain- 
ing in the solution, according to Test 6. The difference 
between the amount of potassium cyanide in 20 cc. of the 
stock solution and the quantity found above gives the amount 
consumed by 10 grammes of ore. 

If the consumption of cyanide is not excessive (which will 
depend altogether on the value of the ore, as rich ores can 


400 | APPENDIX D. 


stand a much higher consumption than those of lower grade), 
or, say, not over 4 pounds of potassium cyanide per ton of 
ore, the following extraction tests can be proceeded with. 

3. Tests for the Percentage of Extraction.—Generally 
two series of tests are made—by agitation and by percolation. 

Agitation.—Take four 4-ounce wide-mouthed glass-stop- 
pered bottles, place 1 assay-ton of pulp in each, then add to 
each 60 cc. of solution of the following strength, respectively: 


OuND ame. O.I per cent KCN. 
66 2: 0.3 ee ¢é 
66 35 0.5 66 66 
6¢ 4, 0.75 66 66 


Before adding the cyanide solution, the proper quantity of 
neutralizer, as determined in Test I, is added. Allow the 
bottles to stand for 48 hours, with occasional shaking. Filter 
off solutions; wash with water up to original bulk; test an 
aliquot portion of the solution for loss of cyanide; dry the 
tailings; crush them to 100-mesh, and assay. From the 
assay of the original pulp and the assay of the tailings, the 
percentage of extraction can be calculated. 

Another method preferred by some is to assay the tailings 
and also assay the solution (see Test 11); then 
Percentage of extraction = 

Assay of solution X Weight of solution & I00 
(Assay of solution X Weight of solution) 
+ (Assay of tailings X Weight of pulp) 

For quick results, the bottles are placed in an agitator 
which is revolved for twenty-four hours. 3 

Several agitation tests can be carried out in this manner, 
varying the quantity of cyanide solution used and the mesh 
of ore (10-, 20-, 30-, and 40-mesh). 

Fercolation.—F¥or these tests a glass percolating-jar pro- 
vided with a false bottom covered with a double filter-paper 
will be found convenient. Such an apparatus is shown in 
Fig. 1. Place 1 pound, or more, of the pulp (with the proper 


APPENDIX D. 407 


quantity of the neutralizer thoroughly mixed with it) on the 
filter, and add to the charge 230 cc. of the stock solution for 
each pound of ore taken. Allow the solution to macerate 
for twelve hours, and then percolate gently for thirty to forty 
hours. Wash with water until the filtrate reaches the original 
bulk. The rate of percolation may be noted here. 








Apparatus for Test by Percolation. 


Test the solution for loss of cyanide; assay an aliquot 
portion of the solution and the tailings, and thus determine 
the percentage of extraction. 

A series of tests may be carried out in this manner, vary- 
ing the strength of the cyanide solution, the fineness of the 
ore, and the time of contact from twelve to seventy-two hours. 

The results of these experiments will prove the applica- 
bility of the process to the ore in question, and the best 
method of treatment, i.e., the strength of solution and the 
mesh which will give the best extraction in the shortest time, 
with the least consumption of cyanide. 

Where it is desired to treat larger quantities of ore, a very 
convenient apparatus is a large glazed earthenware jar, pro- 
vided with a false bottom and an outlet at one of the lower sides. 


408 APPENDIX D. 


The following formula will be found convenient for calcu- 
lating the percentage of extraction: 
Let A = the assay-value of the ore in ounces troy per 
ton of 2000 pounds av.; 
£ = milligrammes of gold found in the filtrate; 
C = pounds av. of ore taken for treatment: 
A = the percentage of extraction. 


13 

A= pO 2010 Vie 

4. Determination of the Cause of Cyanide Consumption. 

—Should the consumption of cyanide be high, the cause of 

consumption may be determined by an analysis of the cyanide 

solution. For every part of cyanide rendered inoperative, a 

corresponding proportion of metal enters solution. Thus one 

part by weight of iron consumes seven parts by weight of 

potassium cyanide, etc. The following equations represent 
the reactions most frequently encountered : 


FeSO, + 6KCN = K,Fe(CN), + K,SO, 
or 
56 (at. weight of Fe) : 390 (mol. wt. 6KCN) :: 1: 7; 
ZnSO, + 4KCN = K,Zn(CN), + K,SO,; 
or 
65 (at. wt. Zn) : 260 (mol. wt. 4KCN) :: 1: 4. 
2 Cu”SO, + 6KCN = K,Cu’,(CN), + 2K,50, + 2CN. 


Salts of aluminium and magnesium act in a different 
manner with potassium cyanide, their hydrates being formed 
with the liberation of hydrocyanic acid, thus: 


Al(SO,), + 6KCN + 6H,O = Al,(OH), + 3K,SO, + 6HCN 
MgSO, + 2KCN + 2H,O = Mg(OH), + K,SO, + 2HCN. 


A preliminary alkaline treatment overcomes this objection- 
able feature, their hydrates being precipitated, which are 
then inert towards potassium cyanide, thus: 


MgSO, + Ca(OH), = Mg(OH), + CaSO,, 


MLL END L&D. 499 


insoluble magnesium hydrate and insoluble calcium sulphate 
being formed. 

Soluble sulphides, formed by the action of potassium 
cyanide on some metallic sulphides, again react to some 
extent on the cyanide, with the formation of sulpho-cyanide 
of potassium, thus: 


ZnS + 4KCN = K,Zn(CN), + K,S 
ReoeeKCN + HO --O = 2KOH + KCNS. 


To determine the cause of the consumption of cyanide 
place 100 grammes of the pulp in a wide-mouthed bottle, add 
200 cc. of the cyanide solution, and agitate for fifteen hours. 
Filter, take 20 cc. of the filtrate (equivalent to 10 grammes 
of ore) and evaporate almost to dryness in a porcelain dish. 
Add some strong sulphuric acid, evaporate almost to dryness, 
and cool. Dilute with water, add some hydrochloric acid, 
and heat to effect solution if necessary. The metal in solu- 
tion may now be determined by the usual methods. 

The strong sulphuric acid at a high temperature decom- 
poses the metallic cyanides, thus: 


2AgCN + 3H,SO,-+ 4H,O = 
Ag,SO, + 2NH,HSO, + 2CO, + 4H. 


Strong nitric acid may be used in place of strong sul- 
phuric; but hydrochloric cannot be used, as it leaves the 
metal in the form of a double cyanide salt, which is soluble. 

The reactions with nitric and hydrochloric acids are: 


AgCN + HNO, -+ 2H,O = AgNO, + CO, -+ NH, + 2H. 
K,Fe(CN), + 4HCl = H,Fe(CN), + 4KCl. 


5. Determination of the Cause of Non-Extraction.— 
Should the above tests show a low percentage of extraction, 
the next step is to determine the cause of this non-extrac- 
tion. It may be due to numerous causes, such as total 
destruction of potassium cyanide by certain salts of the base 
metals present in a form readily attacked by the potassium 


410 APPENDIX D. 


cyanide. The gold may be in a very coarse state, in which 
case the solvent action of the potassium cyanide will be too 
slow for the practical application of the process. The gold 
may be combined or alloyed with tellurium, antimony, bis- 
muth, etc., in which case the cyanide is inoperative until the 
combination is broken up. The presence of soluble sulphides 
in solution. The character of the gangue, such as kaolin or 
talc, which may be present in such quantities as to effectually 
prevent percolation. To overcome these difficulties the 
following methods may be tried: 

In the case of an ore which consumes a latge quantity of 
cyanide, if a preliminary wash with water, weak acid, or alkali 
is ineffective, the ore may be classed as one not adapted to 
the process. 

The coarse-gold difficulty may be overcome by amalgama- 
tion, either before or after treatment with cyanide, which 
generally results in an excellent extraction. The South 
African practice may be cited as an example. 

The difficulty due to the presence of bismuth, antimony, 
etc., in combination or as an alloy with the gold, may some- 
times be overcome by fine grinding and long contact with the 
cyanide solution; but the usual method is to treat the ore to 
a preliminary roast, which converts the gold into a condition 
in which it is readily attacked by cyanide. 

The difficulty due to the presence of soluble sulphides can 
be overcome by the addition of a soluble lead salt or the 
addition of an oxidizing agent. 

Should the ore contain much kaolin or tale, if coarse 
crushing is ineffectual, nothing further can be done, and the 
ore must be classed as'’one non-adapted to the process. 

Ores containing considerable quantities of oxidized copper 
minerals are to be classed as not adapted to the process. 

6. Determination of the Free Potassium Cyanide in 
Solution.—A number of methods have been proposed, and 
there are several which give good results when the solution is 
free from cyanides other than potassium cyanide. With com- 
plex mill solutions containing K,Zn(CN), these methods fail. 


APPENDIX D. all 


With pure solutions, such as the freshly prepared stock 
solution, a rapid and accurate determination may be made by 
titrating a measured quantity of the solution to be tested with 
a standard solution of silver nitrate, using 2 or 3 drops of a 5 
per cent solution of potassium iodide as an indicator. Silver 
cyanide is formed, and immediately redissolves in the excess. 
of potassium cyanide. The reaction is as follows: 


AgNO, + KCN = AgCN + KNO,; 
AgCN -- KCN = KAg(CN),; 


: eh 
or the reaction may be expressed as follows: : 


2KCN + AgNO, = KAg(CN), + KNO,,. 


As soon as all the potassium cyanide has been converted 
into the double cyanide of potassium and silver an additional 
drop of the silver-nitrate solution produces a pale-yellow 
opalescence, owing to the formation of silver iodide. The 
quantity of silver solution added is read off from the burette 
and the percentage of potassium cyanide is calculated. 

In the United States a solution containing 6.535 grammes 
of silver nitrate to the liter is used. The quantity of cyanide 
solution usually taken is 10 cc. When 10 cc. of cyanide 
solution are taken, each cc. of the silver solution used indi- 
cates I pound of potassium cyanide to the ton (2000 pounds) 
of solution. Abroad, decinormal silver-nitrate solution is 
generally employed, the loss in cyanide being obtained in 
percentage on the ore. This percentage multiplied by 20 
gives the pounds of potassium cyanide consumed per ton. 

Another method which answers all purposes, provided the 
cyanide solutions are quite pure, but which is useless for 
complex mill solutions, depends upon the following reaction: 


KCN + 21 = KI-LICN. 


This method requires a solution of pure iodine in potas- 
sium iodide. A solution of pure wheat starch is used as an 
indicator. Ten or morecc. of the cyanide solution are meas- 


4lla APPENDIX D. 


ured off and run into a beaker. A few drops of the starch 
solution are added, and then the iodine solution is run in from 
a burette, with stirring, until an excess of one drop of the 
iodine solution is present, which is indicated by the formation 
of permanent blue iodide of starch. The iodine solution may 
be standardized by some freshly prepared stock solution, or 
preferably by means of a standard solution of sodium hypo- 
sulphite. This method may be used to determine the per- 
centage of KCN in commercial potassium cyanide. 

A number of other methods for the determination of the 
available cyanide have been proposed, but that first described 
is believed to be the best. 

In a well-regulated mill the strength of the solutions is 
tested on each tank every four hours whilst the solutions are 
percolating. | 

The method usually adopted for the determination of the 
free potassium cyanide in mill solutions is as follows: 10 cc. 
of solution-are diluted with distilled water to 65 or 70 cc. and 
titrated with the standard silver-nitrate solution, without the 
use of an indicator. When all the free potassium cyanide is 
changed to KAg(CN), an additional drop of the silver solution 
produces a distinct white opalescence, owing to the formation 
of insoluble zinc cyanide, thus: 


K,Zn(CN), + AgNO, = KAg(CN), + Zn(CN), + KNO,. 


It is probable that this second reaction commences before 
all the potassium cyanide is combined with silver; for on 
partly titrating a solution containing both salts, and allowing 
it to stand, a white precipitate slowly forms. . Hence the 
titration must be performed rapidly, in which case the separa- 
tion of the white precipitate can be taken as marking the end- 
point. The titration requires some practice to be performed 
properly. 

7. Determination of the Free Hydrocyanic Acid in 
Solution.—To 10 cc. of the mill solution add 16 cémoiea 
solution of potassium bicarbonate (containing 15 grammes of 
KHCO, to the litre), dilute to 65 or 70 cc. and titrate as in 


APPENDIX. D. 4110 


fest 6, without the use of potassium iodide as an indicator. 
Upon the addition of the bicarbonate the following reaction 
takes place: 


HCN + HKCO, = KCN + CO,+ H,O. 


The titration gives the HCN in terms of KCN, and KCN 
xX 0.415 = HCN. As this titration gives the potassium 
cyanide and the hydrocyanic acid, the difference between this 
result and that obtained in Test 6, multiplied by 0.415, gives 
the hydrocyanic acid. 

For each cc. of mill solution taken I cc. of the potassium 
bicarbonate solution is used. This will be sufficient for solu- 
tions containing as much as 0.4 per cent of HCN, which is 
much higher than mill solutions usually run, but the excess 
does no harm. z 

The addition of the bicarbonate solution usually causes a 
distinct turbidity, which should disappear when the solution 
is diluted, giving a clear liquid for titration. If, as rarely 
happens, a faint turbidity remains, a duplicate of the solution 
to be titrated is prepared, the end-point being shown by the 
increased cloudiness in the titrated solution as compared with 
the blank solution. 

8. Determination of the Total Simple Cyanides in 
Solution.—To 10 cc. of the mill solution add to cc. of half- 
normal sodium-hydrate solution (20 grammes of NaOH per 
litre), dilute to 65 or 70 cc., add a few drops of the potassium- 
iodide solution, and titrate to pale-yellow opalescence, as in 
deer O, “lhe result is the total KCN, HCN, and’K,Zn(CN),, | 
in terms of KCN. The amount of sodium hydrate to be 
added depends principally on the percentage of K,Zn(CN), 
present, as a large excess should be avoided. The amount 
given will be sufficient for solutions containing 0.7 per cent 
zinc and 0.4 per cent hydrocyanic acid, and will answer in all 
ordinary cases likely to be encountered in mill practice. The 
addition of the sodium hydrate produces a permanent precipi- 
tate, but the use of potassium iodide as an indicator prevents 
any doubt as to the end-reaction. 


All¢c APPENDIX D. 


9. Determination of the Ferro-, the Feri:-, and the 
Sulpho-Cyanides in Solution.—The ferrocyanides and the 
sulphocyanides, if desired, may be determined by titration 
with a standard solution of potassium permanganate in an 
acid solution, the reactions being as follows: 


10K,FeCy,-+ K,Mn,O, + 8H,SO, = 10K,FeCy,-+ 6K,SO, + 
2MnSO,-+ 8H,O; 


1oKCyS + 6K,Mn,0O, + 13H,SO, = 11K,SO,-+ 12MnSO + 
10HCy + 8H,O. 


One portion, acidified with sulphuric acid, is titrated, the 
result representing both of the above compound cyanides. 
To a second portion, acidified with sulphuric acid, a solution 
of ferric chloride is added. ‘The resulting Prussian blue is 
filtered off and the filtrate is titrated with the standard per- 
manganate solution. This second titration gives the potas- 
sium sulphocyanide. 

The permanganate solution should be quite dilute, con- 
taining not more than from 0.3 to 0.5 gramme of potassium 
permanganate to the litre. It may be standardized by any 
of the approved methods, and its value may be calculated 
for the compound cyanides according to the above equations. 

Ferricyanide, if present, may be determined by reducing 
it to ferrocyanide, and then by titration with standard potas- 
sium permanganate as above. 

Should sulphides be present, the shaking up of the solu- 
tion with moist lead carbonate will produce a black precipitate 
of lead sulphide. When present, they must be thus removed, 
by agitation with lead carbonate and filtering off the resulting 
lead sulphide, before the compound cyanides can be deter- 
mined. 

10. Determination of the Zinc and Lime in Solution. 
—As these are sometimes of considerable importance, they 
have to be occasionally determined in the mill solutions. The 
solution is treated in the manner described in Test 4, and 
the lime and zinc can then be determined by conventional 
methods. | 


ee 


APPENDIX D. Alida 


11. Determination of the Gold and Silver in Solution. 
—Numerous methods have been proposed, but the following, 
which is the simplest, is the method generally adopted: 

Evaporate one assay-ton (= 29.2 cc.) of the solution to 
dryness ina lead tray. Moll up the lead and cupel on a hot 
cupel, weighing the resulting button. Alloy the bead with 
silver, if necessary, and part for gold as usual. | 

Should the solution contain over 0.2 ounce of gold per 
ton, the lead should be scorified together with a little borax 
glass prior to cupellation. 

The lead tray is made of pure lead-foil, and is 3 inches 
long, 2 inches wide, and 4 inch deep. It should weigh about 
20 grammes. For the evaporation, the tray containing the 
solution is placed on a piece of asbestos cardboard, heated 
by a burner underneath. 


APPENDIX E. 





THE ANALYSIS OF REFINED COPPER: 


THE following method of sampling a lot of copper is quite 
generally adopted: Each bar or ingot is drilled, the drillings 
being taken clear through the bar. These drillings are melted 
in a clean plumbago crucible, the melt being cast into a bar or 
granulated by pouring into water.* The bar is drilled in 
several places, these drillings constituting the sample. In the 
case of a granulated sample the granulations are reduced by 
quartering for the final assay sample. 

Electrolytic copper may contain any or all of the following 
impurities: Silver, lead, arsenic, antimony, selenium, tellurium, 
bismuth, iron, sulphur, and oxygen. 

Silver.—For the determination of the silver weigh out 30to 
100 grammes, dissolve in nitric acid, and proceed according to 
Chapter IV of Part III, except that it is unnecessary to make 
two filtrations where gold is absent, as is generally the case. 

Lead and Iron.—\ntroduce from 10 to 30 grammes into a 
No. 4 beaker and dissolve in nitric acid (1 part strong acid and 
I part water), taking care to use no more acid thar is neces. 
sary. When solution is effected, heat to expel the red fumes 
and the excess of acid, dilute to 300 cc. with water, add I cc. 
of sulphuric acid, stir, and allow to stand for several hours. 
Filter off the precipitated lead sulphate and wash with a one 
per cent solution of sulphuric acid until the washings are free 
from copper salts. The lead may now be determined ac- 
cording to Chapter IX of Part II, preferably by Alexander’s 
method. 


* The melting of the borings is condemned by Ulke. The Mineral Indus- 


try, Vol. III. 
412 


APPENDIX E. 413 


To the filtrate add an excess of ammonia and heat to boil- 
ing. The iron is precipitated together with arsenic, etc. 
Filter off the precipitate, wash it with hot water until free 
from copper salts, and dissolve it on the filter with a little hot 
dilute hydrochloric acid. Dilute the solution, pass sulphuret- 
ted hydrogen for 30 minutes, filter off the precipitated sulphides, 
wash with sulphuretted hydrogen water, and determine the 
iron in the filtrate with a standard solution of potassium per- 
manganate according to Chapter XVI of Part II. 

Arsenic.—Dissolve 10 to 20 grammes in nitric acid, heat to 
expel red fumes, add a small crystal (about 1 gramme) of ferric 
sulphate, stir, and add an excess of ammonia. Heat to boil- 
ing, and filter off the precipitated ferric hydrate, which will 
contain all of the arsenic. Wash with dilute ammonia water, 
dry, and ignite the precipitate. Weigh the ignited precipitate, 
reduce it to an impalpable powder in an agate mortar, weigh 
out an aliquot portion, and fuse it with 8 parts of a mixture of 
pure sodium carbonate and potassium nitrate. Dissolve the 
fused mass in water, and determine the arsenic according to 
Chapter X of Part II. 

Antimony and Bismuth.—Dissolve from Io to 30 grammes 
in nitric acid, heat to expel red fumes, dilute to about 300 cc., 
and add a small crystal of pure ferric sulphate. Render the 
solution ammoniacal, heat to boiling, add 0.75 gramme of am- 
monium carbonate and a little sodium phosphate. The pre- 
cipitation of bismuth and antimony is complete. Filter off the 
precipitate, wash with water containing a little ammonia, and 
dissolve the precipitate in a little dilute hydrochloric acid. 
Dilute the solution and pass sulphuretted hydrogen for 30 min- 
utes. Add 10 cc. of yellow ammonium sulphide and warm 
gently for one hour. Filter and wash. The filtrate will con- 
tain the antimony, which is precipitated by the addition of a 
little dilute hydrochloric acid. Filter, wash, and dissolve the 
antimony sulphide with a little warm concentrated hydro- 


chloric acid, leaving the arsenic sulphide undissolved. Dilute 


the filtrate, pass sulphuretted hydrogen, allow the precipitated 
antimony sulphide to settle, wash by decantation, and finally 


414 APPENDIX E. 


transfer to a weighed porcelain crucible. Ignite and weigh as 
Sb.O (oee Chapter xl otbartyl i) 

The residue will contain the bismuth, with probably some 
lead and copper. It is dissolved in nitric acid and the bis- 
muth is precipitated with ammonium carbonate and ammonia. 
The precipitate is filtered off and washed with water contain- 
ing a little ammonia. Should the copper not be completely 
separated, redissolve in a little nitric acid and repeat the pre- 
cipitation. Dissolve the precipitate on the filter in a little 
nitric acid and determine the bismuth electrolytically in a 
dilute solution, or according to Chapter XIV of Part II. 
Should the bismuth be determined electrolytically, any lead 
present will not interfere, as it will be separated by the elec- 
trolysis (see Table VI). This method is due to Ray.* 

Tellurium and Selentum.—Dissolve from 25 to 50 grammes 
of the copper in nitric acid, adopting the same precautions as 
in the case of lead and arsenic. Add to the solution one 
gramme of ferric nitrate, stir, and heat the solution to boiling. 
Precipitate the iron with an excess of ammonia, when the pre- 
cipitate will contain all the tellurium and selenium. The pre- 
cipitated ferric hydrate is filtered off, washed with water con- 
taining a little ammonia, and dissolved in a little warm dilute 
hydrochloric acid. To the solution add one gramme of tar- 
taric acid, render alkaline with an excess of potassic hydrate, 
and pass sulphuretted hydrogen for 30 minutes. Filter and 
precipitate the tellurium and selenium in the filtrate by the 
addition of hydrochloric acid. Warm to expel the sulphuret- 
ted hydrogen, and when it is all expelled filter off the sulphides 
of tellurium and selenium. Dissolve the washed precipitate in 
aqua regia, evaporate the solution to dryness to expel the 
nitric acid, repeating the evaporation if necessary, and dissolve 
the dry mass in hydrochloric acid. Pass sulphurous acid gas 
through the solution, and filter off the precipitated tellurium 
and selenium into a weighed filter. Wash the precipitate with 
warm water, allow to stand in a warm place for 12 hours, and 





* The Mineral Industry, Vols. I, II, and III. 


APPENDIX E. AIS 


weigh. To separate the tellurium and selenium place the pre- 
cipitate in a small casserole, add an excess of a strong solution 
of potassium cyanide, and boil. When solution is effected, add 
hydrochloric acid, which will precipitate the selenium, leaving 
the tellurium in solution. Filter, wash, dry at 100° C., and 
weigh the selenium. This method is due to Whitehead.* 

Sulphur.—Place 10 to 20 grammes of the copper in a No. 
4 beaker and add 60 cc. of nitric acid (1.42 sp. gr.) and 15 cc. 
of hydrochloric acid (1.20 sp. gr.). Heat over an aicohol 
flame, and when solution is effected raise the lamp-wick and 
evaporate nearly to dryness. Add 50 cc. of strong nitric acid 
and repeat the evaporation. Repeat the operation, redissolve 
in 300 cc. of water, and add a little nitric acid if a trace of 
basic salt remains undissolved. The addition of hydrochloric 
acid and the subsequent evaporation with nitric acid may 
be dispensed with, provided experiment shows that nitric 
acid alone will oxidize all the sulphur in the material operated 
upon. Pour the solution through a small filter into a 700 cc. 
beaker and dilute with distilled water to 600 cc. Introduce a 
sheet of platinum (4 by 5 inches) into the solution as a nega- 
tive electrode, and as a positive electrode a small coil of plat- 
inum wire. Coverthe beaker with a watch-glass and connect 
the electrodes with the battery or an incandescent lamp circuit. 
Two 16-candle-power lamps, coupled in parallel, will deposit 
the copper in one night. When the copper is all deposited, 
remove the electrodes, wash them with distilled water, allow- 
ing the washings to run into the solution, and filter. Add to 
the filtrate 0.1 gramme (for crude copper 0.5 gramme) of pure 
dry sodium carbonate, and evaporate the solution to dryness in 
a No. 3 or No. 4 porcelain casserole. An alcohol lamp should 
be used, and the solution should be protected from dust, etc. 
When the salts in the dish are dry, heat the covered casserole 
quite strongly, withthe lamp held in the hand, until the acid 
ammonium nitrate suddenly volatilizes, and then allow it to 
cool. 


* Journal of the Am. Chem. Society, Vol. XVII, p. 280. 


416 APPENDIX AL, 


At this point is the only danger of loss of sulphur, hence 
the heat should be just high enough to volatilize the nitrate. 

Add to the residue 10 cc. of strong hydrochloric acid and 5 
cc. of water, and evaporate to dryness onthe water-bath. Re- 
peat this operation and then add I cc. of strong hydrochloric 
acid and 50 cc. of water; heat to effect solution, filter into a 
small beaker, and wash with hot water. 

The only impurity which is liable to be present which will 
interfere with this method is lead. Should any lead sulphate 
remain on the filters, they must be boiled with a solution of pure 
sodium carbonate, and after filtration the solution is acidified 
with hydrochloric acid, and the sulphur removed by precipita- 
tion with barium chloride. The weight of barium sulphate 
thus recovered should be added to the weight of the main 
precipitate. 

Heat the solution of sodium sulphate to boiling, precipitate 
with a slight excess of barium chloride, and allow the precipi- 
tate to settle 24 hours. When rapid results are desired, the 
solution may be kept at a temperature of 75° C. for three 
hours and then filtered. The sulphur is now determined in 
the usual manner. This method is due to Heath.* 

Oxygen.—For the determination of the oxygen a special 
sample should be prepared by filing the bar with a small velvet 
file. The filings are freed from dirt with a pincers, and from 
iron with the magnet. Samples of 5 grammes each are intro- 
duced into porcelain boats, and the boat is placed in a glass 
or platinum ignition tube. The samples in the tube are now 
ignited in astream of pure hydrogen gas in the usual manner. 
The loss in weight of each sample upon ignition represents 
oxygen. | 


—= 





* Journal of the Am. Chem. Society, Vol. XVII, p. 814. 


APPENDIX F. 


THE MECHANICAL ASSAY OF GOLD AND SILVER 
ORES, 


THE assayer is sometimes called upon to test gold and silver 
ores to determine the percentages of the precious metals which 
can be extracted and saved by amalgamation processes. He 
may also be required to test ores of gold, silver, copper, lead, 
etc., to determine whether the ores can be successfully con- 
centrated. Some gold and silver ores are most successfully 
treated by a combination of the amalgamation and concentra- 
tion processes; in fact, a great majority of the gold and silver 
ores of Western America and elsewhere can be treated by 
these methods, in which case combination tests are in order. 
The average mining man seems to have the idea that the 
process to be adopted can only be determined after many tons 
of the ore have been shipped to some working mill and there 
treated. This method of testing an ore by a mill-run presents 
certain advantages and is to be recommended, where it can 
be economically and successfully carried out, but it necessitates 
the mining and shipment of a considerable quantity of ore, 
as it is impossible to make a reliable quantitative test in this 
manner on a few tons of material on account of the difficulty 
of making an accurate “clean-up.” It involves the careful 


supervision of an expert at the mill during the test, while the 
417 


418 APPENDIX F. 


nearest available mill may be far distant, in which case the 
expense involved will be considerable. The nearest available 
mill may be totally unsuited to the proper treatment of the 
ore in question, and a mill which is adapted to the treatment 
of the ore may not be obtainable within hundreds or thousands 
of miles. By this method a great deal of time and money 
may be wasted in making an unnecessary test; on the other 
hand, the results obtained are actual working results, obtained 
in a working mill, and hence appeal to the uninitiated. It is 
the opinion of the author, after many years of practical ex- 
perience in testing ores both in the mill and the laboratory, 
that the laboratory method is preferable in most cases. It can 
be carried out on the ground; it involves less expense; it does 
not involve the actual mining of tons of ore with which to 
make the test; the results may be obtained quickly, and the 
conditions essential to the successful treatment of the ore 
may, in most cases, be determined more accurately in the 
laboratory than they can be in the mill. 

No matter how much engineers may disagree with the above 
statements, they might all well agree that preliminary labora- 
tory tests should always precede the actual mill tests, in the 
examination of a mining property. Many mining districts 
contain the ruins of reduction-works which were erected to 
treat ores which were either wanting in quantity or were 
totally unsuited to the method of treatment adopted. How 
much wasted money could have been saved by a little prelim- 
inary testing? Want of intelligence, or care, in the sampling 
and estimation of ore bodies, and a disregard of metallurgical 
principles and economic conditions, are responsible for a 
majority of such failures. 


{ 


CONCENTRATING TESTS. 


The method to be pursued will depend largely upon the 
appliances at hand and whether this is to be a preliminary or 
a final test. It may happen that the only apparatus obtainable 
are the hand-mortar, bucking-plate, gold-pan, and a few sieves, 


APPENDIX F. 419 


in which case the tests are made by hand. These hand tests 
can hardly be taken asa criterion of what may be actually 
accomplished in a properly constructed mill, but are, never- 
theless, extremely valuable as an indication of what may be 
accomplished, and are frequently all that will be required. 
Fland Tests.—The first step in all tests is a critical eye 
inspection of the ore in order to determine its mineral char- 
acter and approximately the percentages of its various mineral 
constituents. Sometimes this is as far as the investigation 
need proceed, as the inspection may show the ore to be un- 
suited to concentration. If the character of the ore and the 
percentages of the gold-carrying minerals appear such as to 
lead one to believe the ore may be concentrated, the next step 
is to determine how fine the ore should be crushed. This may 
be settled, in a preliminary way at least, by crushing typical 
pieces of the ore and examining the different sized particles 
with the aid of a magnifying-glass. It must be remembered 
that fine crushing is nearly always a disadvantage; but, on the 
other hand, it is necessary to crush the ore sufficiently to 
liberate or separate the valuable minerals from the gangue. 
Having settled the point as to how fine it is desirable to 
crush the ore, a sample of, say, five pounds, is crushed to this 
size. The sample should be crushed in successive stages, the 
fines being screened out as the crushing progresses, in order to 
avoid an undue amount of slimes. The hand-mortar and a 
nest of box-sieves will serve for this purpose. The sieve 
Peamiceana box of the nest shown in Fig. 1 are of tin, the 
sieves, except the 4-mesh, are of brass cloth, and the pan- 
box is 12 inches in diameter. For these hand tests it is not 
desirable to make a number of different sizes, as only com- 
paratively fine material can be treated in the pan, consequently 
the ore is crushed to pass a certain mesh sieve; generally 20 
or 30 mesh will prove to be the proper size. After the sample 
is crushed and screened it is dried on a steam drier, the dried 
pulp is spread out on a piece of rubber cloth, or heavy paper, 
and a sample for assay (about six ounces) is carefully taken. 


* 


420 APPENDIX F. 


The assay sample is pulverized on the bucking-plate to pass a 
100-mesh sieve. From the remainder of the material a sample 
of, say, 4 pounds, is weighed out and concentrated by panning 
in the gold-pan illustrated in Fig. 2. The tailings from this 
panning operation are caught in a large tin milk-pan, or other 
suitable vessel, and allowed to settle. The concentrates re- 
maining in the gold-pan are examined from time to time to 
see if they are sufficiently free from gangue, 
and are washed off into a small tin sample 
pan. When all of the 4-pound sample has 
been treated in this way the tailings are 
settled and examined with the magnifying- 
glass. Should they be found to contain much 
valuable mineral they are repanned, the re- 
sulting concentrates being added to the first 
batch. This operation may have to be re- 
peated once or twice in order to obtain clean 
# == tailings, and even then the tailings may show 
Ziz= considerable valuable mineral in the finer 
Fic. 1. sizes or adhering to the larger particles of 
gangue. In this case the tailings are dried and crushed to 
pass a finer screen, say 50 or 60 mesh. This material is mixed 
with water in a large tin pan and is carefully washed on the 
vanning-plaque or vanning-shovel, illustrated in Figs. 3 and 4. 
The concentrates from this operation are washed into a small 
sample pan and dried, while the tailings are added to those 
resulting from the panning. Each sample of dried concen- 
trates is weighed and a small assay sample is carefully cut out 
of each lot. The assay sample is ground on the bucking-plates 
to pass a 100-mesh screen and assayed. The tailings are also 
dried and weighed, and an assay sample is cut out. The tail- 
ings should be retained for further tests by amalgamation, or 
other methods, should such tests be considered advisable after 
the various samples are assayed. 
The method of calculating the results is illustrated in the 
following example: Ore, iron pyrites; gangue, quartz. 





APPENDIX F. 421 





Assay. Oz. per 
Weight. | Ton of 2000 ibs, 
Ounces, arenes 


Percentage of Total. 











Avoir. 

Gold. | Silver. |Mineral] Gold. | Silver. 
SOUR UNG e ticlinidnd)is cia)» 6s wise 0 o's BOcQn ein 2 6.0 100.00] 100.0 
Concentrates from panning..... OES LE few Ate) 2T3O 113.0210 75.-93) 4505 
Concentrates from vanning..... TOs We sQen e400 2.0.) 13.10) 175,39 
PEA Se reali irrcle eee id eiinis pe 8 ois bs BOs O512) e201 81.2" | 84.02) ~13./5 
MOS et CUSUIMNES). 5... cede ws os. 1.9 3.8 SOG 25 17 
Syaved IMCONCENtrates ......+60. 7.5 15-0 | 88.99] 60.8 


Such tests are, of course, only approximations; and while 
they are not sufficiently thorough to enable one to plan a mill 
for the proper treatment of an ore, they are extremely useful 
in out-of-way places, and will serve as a guide to the proper 
method of treatment to be adopted. Before the engineer can 
make a report as to just how an ore should be concentrated, what 
machines should be used, how the machines should be arranged 
and adjusted, what the probable cost of treatment will be, and 
many other details, several points in the treat- 
Mentwor the ore have to be determined.* 
Assuming that the preliminary tests were 
satisfactory, as in the case of the above ex- 
ample, to determine these points a large quan- Fig 2. 
tity of the ore should be shipped to some concentrating mill 
and treated, or the following machine tests should be made. 

Machine Tests.—For testing small quantities of ore the 
writer knows of no apparatus which is better adapted to the 
work than the Vezin laboratory jig for treating the coarser. 
sizes, followed by the Richards tube for classification of the 
finer sizes, which are then treated on the jig, vanning-shovel, 
or vanning-plaque. 

The Vezin jig, illustrated in Fig. 5, was designed by Mr. 
Henry A. Vezin, of Denver, Col., for the purpose of, making 





* The reader is referred to the author’s articles on ‘‘ Concentration of 
Gold Ores,” published in Mines and Minerals for April, May, June, July, 
and August, 1897. 


422 APPENDIX F. 


concentrating tests in the laboratory. Mr. Vezin has also de- 
signed a jig with a bed 6 by 12 inches, having six times the 
capacity of the smaller one, and being also arranged for hand 
power, though it was found best to use a 2-inch belt and power 
for driving it. This jig is useful for treating samples of ore 
from 600 to 1000 pounds in weight; but the small jig will 
generally be found most convenient. The jig consists of a 
screen compartment A, connected with the hutch, as in the 
ordinary large jig. Into the compartment J is fitted the screen- 
box /. In the illustration, one of the screen-boxes is shown in 
place in the machine and two extra boxes are shown on the 





We 
FIG. 3. Fic. 4. 


table. The screen-box in place is provided with a stay-box P, 
and is used when fine material is treated or where it is desirable 
to jig under water. The screens and plunger are 3 by 4 inches, 
and the plunger has a clearance all around of », inch. In a 
later machine the screen-boxes are dispensed with, the screens 
being held in place by brass collars attached to the jig com- 
partment and held together by means of clamps. The screen 
compartment, hutch, plunger compartment, and screen-boxes 
are of No. XX Xtin or No. 22 brass. The screens are of woven 
brass wire. The plunger compartment, shown at B, is pro- 
vided with a brass piston with rubber packing. The plunger 
rod is operated by an eccentric D, arranged so that the stroke 
can be readily varied from oto It inches. The machine may 
be operated by hand by means of the crank G and the gear- 


APPENDIX F. A423 


wheels & and F, geared 3 to 1, so that without moving the 
hand very quickly a speed of from 200 to 240 revolutions can 
be attained. The machine may also be driven by power by 
means of the small wooden pulley K and the friction gears C 
and LZ. This friction gearing is thrown in or out by the spring 
NV, and the small wheel Z is adjustable on the shaft, so that 





the number of strokes can be readily varied. The large disk C 
has three rings, marked respectively 100, 200, and 300. These 
represent the revolutions per minute which the eccentric will 
make when the disk revolves at 100 revolutions per minute. 
When driving by power the pinion & is removed, so that the 
wheel and crank may remain at rest. The jig which Mr. Vezin 
had made for the author was provided with three screen-boxes, 
as follows: 44 inches deep, 20-mesh cloth, openings 0.039 inch ; 
4 inches deep, 30-mesh cloth, openings 0.024 inch; 3 inches deep, 
60-mesh cloth, openings 0.010 inch. If it is desirable to increase 
the depth of the bed, it can be done by fitting a small tail- 
board at the discharge end. 
When jigging screen-sized material, the separation takes 


424 APPENDIX F. 


place in the upward stream, in still water or in a slow, down- 
ward stream ; hence water must be supplied under the plunger. 
This is accomplished by carrying a stream to 
the plunger compartment and maintaining 
the water in this compartment at a higher 
level than that in the jig compartment. When 
water-sorted material is jigged, the separation 
takes place in the downward stream ; hence 
no water is admitted in the plunger side, but 
it is allowed to flow in with the ore on the 
feed-hopper. The feed-hopper has a groove 
in which a bit of rubber packing can be 
slipped under the inclined bottom, so as to 
contract the opening and prevent the water 
from stirring up the ore as it falls upon the 
water and ore in the screen. When greater 
suction is desired the 4-inch bib-cock in the 
rear can be partially opened. The finer 
screens are provided with a stay-box, so as 
to jig under water if desired. Place a plug 
Fic. 6. from above in the discharge of the stay-box, 
and open intermittently, or provide the plug with a side-open- 
ing, to allow a continuous discharge. 

The number of revolutions and the length of stroke are 
largely a matter of experiment. Each different size can be 
experimented with until these points are determined, when the 
ore, concentrates, and tailings can be mixed together and the 
test can then be made under the proper conditions. As a 
general rule the total throw should be two and a half to three 
times the diameter of the grains of ore so as to separate the 
particles sufficiently to enable them to arrange themselves ac- 
cording to their specific gravities. The speed must be suffi- 
cient to raise them. The greater the throw the less the speed, 
and vice versa. The following are recommended when treat- 
ing an ore containing iron pyrites and gangue, the ganzue be- 
ing essentially quartz and feldspar: 





APPENDIX F. 425 





Sizes. 
Sec ey aoteas base T teers iy | a Der at Bee 
Mesh per Diameter in 
Linear Inch. Inches. 
\%’-— 4 mesh 0.250-0.157 I 160 3 
4-6 * O.157—-0.110 % 160 3 
6-10 ‘ 0. II0-0.079 % 160 3 
rOl-r4. 0.079-0.055 % 180 3 
14 -20 ‘‘ 0.055—-0.039 5/16 200 2 
BOr-30. =i 0.039-0.024 3/16 230 2 
atew atetes1 26 [ons ess sss ss. 3/16 290 2 
MALIA SIZO Ros os eas ees os 3/16-1/8 290-310 2 





The concentrates are removed from the sieve by skimming 
with a straight piece of tin about eight inches in length, slightly 
narrower than the sieve-box and bent at a right angle at one 
end. The straight piece is used for skimming and the right- 
angled piece for removing the concentrates from the screen. 

The Richards sorting-tube * illustrated in Fig. 6, was de- 
signed by Prof. Robert H. Richards of the Massachusetts In- 
stitute of Technology to obtain experimental data on water 
sorting in upward currents. It is a convenient laboratory sub- 
stitute for the spitz-lutte or hydraulic classifier of the mill. 
Hydraulic water is fed at ¢, at a constant rate, admitted by a 
dial-cock at constant pressure, guaranteed by an overflow col- 
umn pipe to give a constant head. This passes up and over- 
Pewerate2 ateany cesiréd speed. The fine ore is fed at a, in 
small quantities at atime. The grains become subject to the 
action of the current at 0. If they are light enough to rise in 
the current flowing at any given time they are discharged at 2. 
If heavy enough to fall, they pass down to the bulbg. A ro- 
tary motion is given to the water in d, to prevent a downward 
current on one side and an excess of upward current on the 
other. Two products are obtained at each operation, over- 
flow grains at z and settled grains at g. The overflow from z 
is retained for subsequent treatment, that is, further water 


ee) 





* Trans. American Institute of Mining Engineers, Vol. XXVII. 


426 APPENDIX F. 


sorting with a different upward current. By varying the 
velocity of the upward current at each operation, a number of 
water-sorted. products are obtained. The various minerals 
contained in each of these products may then be separated by 
jigging (for the coarser sizes) and vanning (for the finer sizes). 

The method of calculating and tabulating results is illus- 
trated in the following table, the ore being iron pyrites with a 
quartz and feldspar gangue: 








Assay per Percentage 
Weight ton 2000 lbs. saved.. 


Avoir. : 
Gold. | siivet-| Gold. /Sivers 


photalore taken fOr, CeStr cine sfasistsiemiieeicte seems ier 50.00 0.70 3-0 
Through 4- and over 8-mesh jig concentrates...... I.gt 5-50 15.0 30.01 19.1 
Through 8- and over 1o-mesh jig concentrates, .... 1.52 5.90 18.0 25.62 1832 
Through 1o- and over 20-mesh jig concentrates.... 0.85 6.10 | 24.0 14.81 13.6 
Through 20- and over 30-mesh jig concentrates ... 0.45 6.565|) 385.0 8.36 10.5 
Pirst-water-size concentrates wii. a) ee aslo eee 0.24 8.00 | 41.0 5.50 6.5 
Second-water-size concentrates from vanning...... O219 9-80 | 50.0 3-64 4-3 
Third-water-size concentrates from vanning....... 0.10 | 11.00 | 68.0 Buta 4-5 
rota concentrates jy, sates ere sale tatters ; 5-20 91.08 | 76.7 











Amalgamation Tests.—As stamp-milling and amalgamation 
is the cheapest of all processes for the extraction of gold from 
ore, it is the method most universally adopted. Unfortunately 
amalgamation only saves such gold as is metallic and bright. 
After the upper oxidized part of our gold deposits is passed 
the character of the ore changes to sulphides, and sometimes 
tellurides ; in which case only a portion, or none, of the gold is 
in a state so that it can be saved by amalgamation. Hence 
stamp-milling is frequently followed by concentration to save 
the gold contained in the sulphides and other minerals. In 
certain cases the concentration process is first adopted, and the 
tailings from concentration are recrushed and treated by amal- 
camation for the extraction of the free gold which has not 
been caught by concentration. 

The most satisfactory method of testing an ore to deter- 
mine whether its gold contents can be saved by amalgama- 


APPENDIX F. 427 


tion is to ship several tons, the larger the quantity the better, 
to some mill and have an actual working test made. How- 
ever, this is not always feasible, and 
laboratory tests frequently have to 
be made. These laboratory tests on 
small quantities of ore are also some- 
times of considerable value in con- 
nection with the concentrating tests 
previously described. 

For testing samples of several 
hundred pounds by amalgamation, 
the laboratory. pan or the “clean- 
up” pan of the mill, shown in Fig. 7, is extremely useful, and 
the results of tests, made by this apparatus, should be closely 
duplicated by the commercial results obtained in a mill. How- 
ever, such apparatus is not always obtainable, and tests on 
small quantities, with the aid of simple apparatus, may be re- 
quired. 

For testing small quantities of ore to determine the per- 
centages of gold and silver which can be extracted by amalga- 
mation the reader is referred to Chapter IX of Part III. 








\ N 
lit! 





i 


NGI 
ing 





! 


Fic. 7. CLEAN-UP PAN. 


APPENDIX G. 


THE CALCULATION OF COPPER MAT ie 
FURNACE CHARGES: 


THIS appendix is added as a supplement to Chapter III of 
Part IV. The problem is not simple, owing to the continually 
varying conditions and the many different points which have to 
be considered, the most important being as follows: 

furst—The charge must be calculated so as to produce 
a slag which will be good both from a metallurgical and an 
economic standpoint. A good metallurgical slag is one which 
is fusible, is adapted to the ores to be smelted, should keep the 
furnace in good condition, should allow a good separation 
of the matte, and hence should have as low a specific gravity as. 
possible; should be low in both copper and silver, and should 
usually permit of a high degree of concentration of the copper 
into the matte. An economic slag is one which will fulfil the 
above conditions and at the same time allow an economic mix- 
ture of the ores to be treated so that a minimum amount 
of costly fuel and flux will be required. The addition of flux 
to the furnace-charge not only increases the smelting cost, 
as for each pound of flux required one pound less of ore can be 
treated, thus involving an additional labor and fuel expense for 
the ore smelted, but it diminishes the available capacity of the 


plant. 48 


APPENDIX G. 429 


In copper matte smelting the percentage composition of the 
slag is not of the same importance as in lead smelting, where 
the metallurgist is restricted to certain type slags of fixed 
chemical composition. The lead smelter must adhere to these 
types, which have been well established, in order that eco- 
nomical work may result. The copper metallurgist is simply 
restricted within rather wide limits as regards the percentages 
ot slag-producing elements which may be present. While the 
type slags of the lead smelter may be used in copper smelting, 
they are generally uneconomical, as they are quite basic and 
require a large amount of flux for their production. They 
fulfil all the requirements of a good metallurgical slag, but 
in most localities cannot be produced without the addition of 
considerable limestone, and possibly other fluxes, to the charge. 

The limits of the principal slag constituents in copper matte 
smelting may be stated as follows: 


oS NOLS ae hs Oh ee ee ee 26 to 45%. 
Pe i aa so, otpice wd o's en Pe O to 20%. 
SS 3 66 Sg ee 18 to 65%. 
TOL so cas cc NCR Ae ea O to 284. 
ree en fol e ec oois) atasl doe eles ¢ Sie o's oO to 14%. 


In this table MnO is regarded as replacing FeO, and BaO 
and MgO as replacing CaO. Manganese replaces iron and 
renders the slag extremely fusible. It was formerly considered 
as having a tendency to carry silver into the slag, and conse- 
quently as detrimental. Iles* and Church,t however, have 
demonstrated that it is not detrimental, and Church claims to 
have made slags containing over 43% MnO which were remark- 
ably low in silver (0.5 oz. per ton). 

The presence of MgO and BaO in copper slags is not as 
objectionable as in lead slags where under 4% of either oxide is 


* School of Mines Quarterly, Vol. V, p. 217. 
+ Trans. Am. Inst. M. E., Vol. XV, p. 612. School of Mines Quar- 
terly, Vol. V, p. 322. 


430 APPENDIX G. 


generally regarded as the safe limit. Copper matte slags have 
been successfully run with as much as 12% of these oxides. 
The presence of BaO is objectionable, as it raises the specific 
gravity of the slag. The presence of zinc is objectionable 
in both lead and copper smelting, as it has a tendency to render 
the slag thick and infusible and consequently increases the slag 
loss in valuable metals. It also has a marked tendency to 
increase the loss of silver by volatilization during the roasting 
or smelting operations. In lead smelting 13% of ZnO in the 
slag may be regarded as the maximum limit, but in copper 
smelting slightly higher limits have been reached. All slags 
contain other constituents, as Na,O, K,O, PbO, Cu,S, CaS, etc., 
which are generally present in small quantities, so that the sum 
of the SiO,, FeO, MnO, CaO, ZnO and Al,O, may be taken as 
forming from go to 95% of the slag, except when much MgO or 
BaO is present. The action of alumina in these slags has been 
the subject of much speculation and discussion, and more exact 
information on this important question is needed. In the 
highly ferruginous slags of the lead and copper smelter, alumina 
usually plays the part of an acid, but slags are occasionally en- 
countered in which the alumina is present as a base. 

The specific gravity of the slag is an important point. The 
loss of silver and copper in the slag will depend largely upon 
the difference in specific gravity of the matte and slag. The 
specific gravity of the ordinary matte may be stated as from 
5.0 to 5.5, whilst that of the slag is from 3.50to. 4.75 neue 
essential that a considerable difference in specific gravity (1.75 
about) should exist between the matte and slag in order that a 
good separation may be effected. Of course, the greater the 
difference, other things being equal, the more perfect the 
separation. 

Second. The furnace charges must be arranged so as to use 
up the ores on hand and the daily supply in about the propor- 
tions in which they exist. This requires that the ore buyer, or 


. mine superintendent, and the metallurgist should keep in 


APPENDIX G. 431 


touch with each other and be familiar with the requirements of 
each. . 

Third. The charges must be calculated, as near as possi- 
ble, so that the resulting matte will be of the proper grade for 
shipment or for its further metallurgical treatment at the 
works. This is frequently a question of great importance, as, 
for example, suppose the matte is to be treated for blister 
copper by bessemerizing at the works. In the United States 
it has not so far proven profitable to bessemerize mattes con- 
taining much less than 50% copper. When the matte is 
shipped to a distant refining-works for further treatment the 
freight and refining charges are items which cannot be disre- 
garded in the calculation of what will be the most profitable 
grade of matte to produce. The percentage of copper in the 
furnace charge and the fall of matte will also have an influence 
on the loss of silver and copper in the smelting operation. 

Fourth. The amount of sulphur, arsenic, and antimony 
which will be volatilized in smelting is of the greatest impor- 
tance, and upon this many of the other questions will depend 
to a large extent. This has a direct influence on the rate of 
concentration, the grade of the matte, and the consumption of 
fuel, all questions of vital importance. This facotr is ex- 
tremely variable, the amount volatilized being from 84 in 
ordinary matte smelting to probably 90% in true pyritic smelt- 
ing. It depends upon the construction and operation of the 
furnace and upon the physical and mineralogical character of 
the ores. Depending upon so many variable considerations, it 
is impossible to formulate any rule which will serve as more 
than a guide in the calculation. A safe rule can only be 
arrived at after the furnace has been in operation for some 
time and after numerous experiments have been made. Even 
then no absolute rule can be formulated, as conditions will 
necessarily vary from time to time. In connection with this 
question it should be remembered that for pyritic smelting 
the amount of sulphur consumed by oxidation must be large. 


S&S 


432 APPENDIX G. 


True pyritic smelting requires at least 65% of pyrites, or equiv- 
alent sulphides or arsenides, on the furnace charge in order 
that sufficient heat may be generated to smelt the mixture. It 
is true that partial pyritic smelting is successfully carried on 
with a smaller percentage of pyrites, using carbonaceous fuel 
in the furnace, and limestone as a flux to supply the deficiency 
in basic elements on the charge. 

Fifth. The character, or chemical composition, of the re- 
sulting matte must be considered. This will depend upon the 
mineralogical character of the ores, the volatilization of sul- 
phur, arsenic, antimony, zinc, and lead, the operation of the 
furnace and the character of the resulting slag. As these are 
all variable no exact rule can be formulated for the determina- 
tion of this question. Until the works have been in operation 
for a sufficient time, so that the question can be settled by 
frequent analyses of the matte, the following rule will serve as 
a guide: 

1. From the total S, As and Sb on the charge, deduct such 
amount as will probably be volatilized (in ordinary matte 
smelting this may be taken as 10%). The balance is to be con- 
sidered as S, etc., available for matte. 

2. Calculate all of the copper present to Cu,S. 

3. Calculate three-quarters of the lead present to PbS. 

4. Calculate one-half of the zinc present to ZnS. 

5. Calculate the remainder of the available sulphur to FeS. 

These sulphides will usually constitute from 90 to 95% of 
the matte. The remainder will be slag mechanically mixed 
with the matte, probably metallic iron, and other sulphides, 
arsenides and antimony compounds. The matte may also con- 
tain sulphides and arsenides other than the simple ones 
enumerated. The true composition of matte has never been 
accurately determined, and a thorough investigation of the 
subject would be of great benefit to modern metallurgy. 

The calculation is illustrated by the following example: 


APPENDIX G. 433 


ANALYSIS OF ROASTED ORE. 


SNL 2 cs cits OES ee Ce 25% 
i aes shastis cays iene «nis eas 08 40% 
DO asc, SRS GLEE es ce ee ro 10% 
oie rehire. oe ssieup oo nce sialhitie ss 4 0:8 4.5% 
DE cynics og ee ene Po 3% 
Se es aise sis4 ah skis olt sinose tek ot 7% 


Assuming that 10% of the sulphur will be volatilized, we 
have 6.3 parts of sulphur available for matte in each 100 parts 
of ore. 


Diem taGu,: Mol. Wt. Cu,S = Parts Cu parts Cu.ot 


126 : 158 = 10 eel in. 
Peete by: Viol, Wt. Pbs. = $ Parts Pb : Parts PbS. 
207 : 239 ae! Baits 
Peeve nes Mol Wt. ZnS5 — 4 Parts Zn =: Parts ZnS. 
65 : Q7 = 2.25 ee 2. 307 


The sum of these sulphides is 17.48 parts. This, less the 
sum of the metals (14.5), leaves 2.98 parts of sulphur, which 
combine with the Cu, Pb and Zn, leaving (6.3 — pe) 3.32 
parts of sulphur to combine with the iron. 


Ate wtos: Mol. Wt. FeS = Parts S : Parts FeS. 
Bat at 88 nn) 2 eee OL 


If we assume that the Cu,S, FeS, PbS and ZnS constitute 
90% of the matte, for the parts of matte produced, we have 


17.48 + 9-13 _ 


ae 29.5 


and for the percentage of copper in the matte 


Boece at == 100°? 4014 4 2.0%. 


This figure is too high, as no allowance has been made for 
loss of copper in the slag. 


434 APPENDIX G. 


The next step in the calculation is to determine whether 
sufficient iron is present to form a good slag. For iron avail- 
able for slag we have 46 — (9.13 — 3.32) or 40.19 parts, which 
is equal to 51.67 parts FeO. If we assume that the SiO; and 
FeO constitute 90% of the slag, we have 


2? = 85.18 parts of slag produced. 
Its composition is as follows: 
a = 29.3% SiO, 
ee =_— — 60.6% FeO, 


This shows the resulting slag to be somewhat high in iron 
and low in silica. This might be obviated by leaving more 
sulphur in the roasted ore, which would result in a larger 
amount of iron going into the matte; or, should silicious ores 
be available, sufficient silica in the form of ore could. be added 
to produce a slag of the proper composition. The necessary 
fuel to be added to the charge will also supply some of the 
deficient silica. 

Sixth. The furnace charge should have the proper weight, 
which will depend principally upon the size of the furnace and 
somewhat upon the character of the ores. The weight of the 
charge will have a direct bearing upon the practical working of 
the furnace. It will vary from 2000 to 4000 pounds, accord- 
ing to the conditions, the proper weight having to be deter- 
mined by actual experiment in each individual case. 

Seventh. The amount of fuel to be added to the charge and 
the amount and composition of its ash are important points. 
The amount necessary will depend upon its character, the 
character of the ores, the composition of the slag, and the 
operation of the furnace. In ordinary matte smelting, where 
only a small percentage of the sulphur present is volatilized, 
from 10 to 15% of good coke will be required. By fuel per. 


APPENDIX G. 435 


centage is understood a percentage of the ore and flux charge. 
This estimate is based upon a good, firm, porous coke contain- 
ing about 12% ash. As the percentage of ash increases, or the 
quality of the coke deteriorates, the amount used must be 
increased. As the amount of sulphur, arsenic, or antimony 
volatilized increases, the percentage of carbonaceous fuel re- 
quired decreases, until in the case of true pyritic smelting no 
carbonaceous fuel is added to the charge, the combustion of 
the sulphur, arsenic, etc., together with the hot blast intro- 
duced at the tuyeres, supplying the necessary heat-units. 
Eighth. The loss of gold, silver, and copper in the smelting 
operation demands consideration. These losses will vary 
according to the grade and character of the ores and matte, 
the character of the slag, the operation of the furnace, and the 
facilities provided for the coilection of flue-dust and fume. In 
true pyritic smelting (the operation being one of oxidation) the 
losses will be greater than in ordinary matte smelting, where 
the action is reduction. The presence of copper in the charge 
will have a marked effect on the gold and silver losses, even 
small amounts having a marked tendency to increase the con- 
centration of the precious metals in the matte. In ordinary 
matte smelting the loss in gold should be practically zz/, and 
the silver loss should not exceed 5% of the assay value of the 
ore. The copper loss will depend principally upon the amount 
and character of the slag produced. With ordinary mattes, 
containing as much as 40% copper, a good slag should not con- 
tain over 0.6% copper. Under exceptional commercial condi- 
tions, it may prove profitable to make slags assaying consider- 
ably higher; but in good work, and under ordinary conditions, 
the slags rarely exceed 0.5%. The amount of zinc present may 
largely affect the gold and silver losses, The zinc oxide which 
is volatilized invariably carries off mechanically both gold and 
silver. These losses may be reduced by the introduction of 
proper dust- and fume-saving apparatus, but cannot be entirely 
obviated. Zinc also makes bad slags, and hence increases the 
loss of gold, silver, and copper in the slag. The production of 


436 APPENDIX G. 


a matte of as high, and a slag of as low, a specific gravity as 
possible, and the use of efficient settling and separating appara- 
tus will also largely determine the losses. 

The calculation of the charge is illustrated by the following 
examples: 

Example No. 1. The works have a smelting capacity of 300 
tons per 24 hours. Ore A, which is roasted, is practically 
unlimited in quantity, coming from mines belonging to the 
smelting company. Ore B can be purchased to the extent of 
75 tons per day, and ata fair profit. The matte is shipped and 
sold to refiners. The assay of the ores is as follows: 


Ore | SiOg%| Fex | Cug | Pbg| Zn%| S% | AlgOs%| CaO% |O,, pote britee ton. 


ed) |e, (nes) ee ee eS SS ee a a a ee 


A 25 46 TO 3 3 7 rs 0.5 
B 50 5 3 2 10 2 50 O.I 
Coke 6 r (as}|h ro|%) 2 I 





Assuming that we will smelt about 250 tons of ore A and 
50 tons of ore B per day, and want a furnace charge of about 
3000 pounds, we have, for pounds of each constituent of the 
charge: 























Ore SiO, Fe Cu } Pb | Zn | Ss | Al,O, Cau e@ze: Ozs. Pounds 
: Ibs. Ibs. | lbs. | lbs. | lbs. | Ibs. lbs. Ibs. Ag Au per charge. 
A 625 | 1150 | 250] 75 | 75 | 175 18.75| 0.625 2500 
B 250 25 15 Io} 50 60 | 12.50] 0.025 500 
Coke]}] 22 4 7 4 360 


—_—_ | J | J | | J | | 


Total | 897 | 1179 | 265] 75 | 75 | 185] 57 64 | 31.25} 0.650 





Assuming that 10% of the sulphur is volatilized, we have 
166.5 pounds of sulphur available for matte. Calculating the 
copper to Cu,S, two-thirds of the lead to PbS and-one-half of 
the zinc to ZnS we have 


APPENDIX G. 437 


Perens — 20554; 21 332.3 lbs. Cu.S 
Somes 500 17. y= 57:7 Ibs. PbS 
OO = 00375) 2S =e 55-0 lbs. ZnS 


352-5 445.9 


and 445.9 — 352.5 = 93.4 pounds of sulphur combining with 
the Cu, Pb, and Zn. This leaves (166.5 — 93.4) 73.1 pounds of 
sulphur to be calculated to FeS. We have 


eee oi 7 Sales fest) —— 2OL lbs. es; 
Hence for iron available for slag we have 1179 — (201 — 73.1) = 
1051 pounds. As some zinc, lead, copper, and small amounts 
of other elements which are usually present, pass into the slag 
the SiO,, FeO, CaO and Al,O, will usually form about g3 4 of 
the slag constituents. Hence we have for the pounds of slag 
produced per charge: 

897 + 1051 X patna! + 64 

0.93 


The composition of the slag will be as follows: 


2547. 


a = 35.2 % SiO,. 
aa SS cues lenclO} 
Te eae ALO. 
Se = 2.6 @ CaO. 


This slag should run well and give a good separation of 
matte, but is somewhat high in iron and low in silica. Should 
a more acid slag be desirable it may be obtained by slightly 
increasing the amount of ore B. 

Before calculating the amount and the composition of the 
resulting matte it is necessary to make allowance for the loss of 


438 APPEND IXGG.: 


copper in the slag. Assuming the resulting slag will assay 
0.4% copper, we have 10.2 pounds of copper to deduct from 
the total copper present, the remainder being that going to form 
matte. This is equivalent to 12.7 pounds of Cu,S. If we 
assume that the Cu,S, PbS, ZnS, and FeS form 934% of the 
matte, we have 


(445.9 — 12.7) + 201 
0.93 


The percentage of copper in the matte is 


= 682 lbs. of matte. 


265 — 10.2) X 100 
idee) SES = 37.3%. 


Allowing for a smelting loss of 5% silver and 1% gold, we — 
have, for the assay of the matte: 


.68 
POON TSS ES = $7.06 02s. Ag =per tou. 


6 2000 
POTS As = 1.88 ozs. Au per ton. 


Example No. 2. We have the following ores to smelt, the 
capacity of the works being 300 tons perday. Ore A is pur- 
chased at a small profit and stall-roasted. Ores B and C are 
purchased at a good profit, and whilst ore C is a heavy sulphide, 
the local conditions are such that it would be inadvisable to 
roast it. The matte is shipped and sold to refiners. The ores 
assay as follows: 


Ore | SiOa% | Fex Cuz Sé CaO% | Pbs ink ones ton. One ae ton. 















































A 10 55 12 7 5 0.3 
B go 5 I 15 I.0O 


























C 15 25 5 35 5 4 6 20 0.5 


Assuming that we smelt 200 tons of ore A, 50 tons of ore B, 
and 50 tons of ore C per day and wish about 3000 pounds on the 


APPENDIX G. 439) 


furnace charge, we have, for the pounds of the different con- 
stituents on the charge: 

















































































































ee ees, | ths | ibe | bs. | ibs. | OF. | Gas, | charge 
A 200 | IIO0O 240 140 5.00] 0.300 2000 
2) Gre ia ee ee ee 
Cc 75 125 25 175 chee 20 30 5.00 ee ite 2 

Total) 725°} 1250 270 315 25 20 30 |°13-75)'0-675 ea fee: 


Calculating the Cu to Cu,S, one-half the Zn to ZnS, two- 
thirds of the Pb to PbS, and assuming that 8% of the sulphur 
is available for matte, we have: 





esos ror es syelnlsic oissiee eisem > wie a 338.5 
PbS 8 Ag Bg Cgc: GAO EO eee ere Tia 
eM 1h 0 Pe sc hos osu digo Se essa oi ones 22.4. 
FeS Sa RS Ni Sees Ee SR a a ae ea 478.8 

855.0 


Which leaves 1215 pounds of FeO available for slag. If the 
SiO,, FeO, and CaO form 90% of the slag, we will have 2183 
pounds of slag produced per charge and its composition will be: 


BS rs eee kik) dob slate skeen ue cetmeles 33.2% 
ED on nosy eos ERS ye ae 55.0% 
SE re go nin oie lg ala rake eens sien ona selared » 1.2% 


This slag is slightly basic, hence the weight of ore B might 
be increased to advantage. Using 700 pounds of ore B, we 
will have 2397 pounds of slag produced per charge, and its. 
composition will be: 


Ee elvis a <ic'n ie ole’ sy 0's sac vieteitins va/a'niie de 37.8% 
OO 8 arene Bee alle vrenacere or etohenshcienetcrs oes 51.1% 
SNIP eros o ishy oie 05's soni dipe tialee’nceim etn nies 1.1% 


If the slag assays 0.5% copper and the Cu,S, PbS, ZnS, and 
FeS constitute 93% of the matte, the percentage of copper in 


440 APPENDIX G. 


the matte should be 27.4. It should assay 32.6 ounces silver 
and 1.72 ounces gold per ton, assuming a 5% silver loss and no 
loss in gold. 

Example No. 3. It is desired to erect a plant for the con- 
centration of the copper and silver contained in an ore of the 
composition given into a matte for shipment. Upon roasting 
at acost of $1 per ton the ore yields a product of the com- 
position shown. With coke at $8 per ton the estimated cost 
of ordinary matte smelting of the roasted ore is $4 per ton, 
and the estimated cost of pyritic smelting of the raw ore is 
$3.25 per ton. Freight to the refining-works on each ton of 
matte is $10. Which will be more profitable, ordinary matte 
or pyritic smelting ? 

Raw Ore. Roasted Ore. 


11 @ Fame Mees ai shai tes Hon rik? 15 % 17.5% 
Hey eae eRe epee «eve nennate 34 % 39.0% 
CU Fo eae yale Pak ees aad le Tee ee 4.1% 4.7% 
CFO Prema mum aig senate cals Lut. 3 % 3.5% 
SO dak dca ye Wel sede! 4 9oo fe eestor koe an eae 40 &% 7 % 
ARES, BS Ca Rowe areca iratecahee ae eee 20 Ozs. 23 Ozs. 


One ton of raw ore yields 1720 pounds of roasted product. 
We will assume that in ordinary matte smelting 90% of the 
sulphur will pass into the matte, while in pyritic smelting only 
20% of the sulphur is available for matte. Calculating the 
charges as before and assuming that the Cu,S and FeS con- 
stitute 95% of ths matte and that the SiO,, FeO, and CaO con- 
stitute 99% of the slag, we have: | 


Pyritic Smelting. Matte Smelting. 
Matte produced per ton of crude ore, 511 pounds. 361 pounds, 


Slag “i 2S eo et OO Samm TOO2) 3 
Copper in:mattel sy. ae eer ee 15.2% 21.6% 
Cost of smelting per ton of crude ore, $3.25 $3.44 
Sa LVE SELIG wares _ peel ase -1.00 
Freight on matte “ s inne be 1.82 








Votalicostress sci ste sire oncfe ieee $5.80 $6.26 


APPENDIX G. 441 


The slags will have the following composition: 


From From 

Pyritic Smelting. Matte Smelting. 
BIE oie col wcee'c cele cs 30.9% 27.4% 
LOG) a anh a ch re 57.9% 62.0% 
Can Ba ealee 6.24 5.6% 


The slag resulting from pyritic smelting is somewhat the 
best and should give a better separation of matte than that 
resulting from the matte-smelting operation. Taking this fact, 
and also the loss of silver in roasting, into consideration, the 
total losses will probably be about the same by either opera- 
tion. With such an ore, under the conditions given, pyritic 
smelting would appear to be the cheapest process. However, 
the difference of $0.46 per ton in favor of pyritic smelting 
would probably be more than offset by the refining charges on 
the increased amount of matte and in consequence of its 
lower grade. 





INDEX. 





A 
PAGE 
Absorbents used in the Analysis of Gases...ccccccccccccccccccccecceess 272 
ee a btion, Determination of Carbonic Acid see Py arian ear rece eave to 
# SSoulphur bye. Sale siaerele( sas eiedie's tielace’s 96, 99 
aii i MANY OLOLELYY vosteuels eure! crete siotee ate pie wheiet ele ee ore 120 
Acetate of Ammonium (Solvent)......... Maite weletet eo herd uy wile wee Gates sistent 70 
Bere sodinm (Precipitant).. 1... e0e A ian ciate mipiaian sata plete lerese nth aie clo eats ts ie”: 
ee oe (solvent) he tr ee aa miatatss ate xia tela outer ent etre cao! ate biehe' a cio eeeeyo 
a Peay SIS VOL COMMELCIal (< cesjc once nance ces 6 ACS ecerees 207 
Acid, Citric Aaclvcat) ie Gee ae are hati steres haie Gaceteieceetale iy gale sheipiure whtuennent 70 
Acidimetry and Alkalimetry.....cccscscsess ure sidaineliveaipvelne tivinie a aie es cece 202 
Acid, Hydrochloric (Solvent)... .seccesccscccsececes Ja wma E Sa atede ti elkta ets 69 
eee tivoronuoric (Plux)........ weioG yes 5's nas Fae se iain gee wea crekustc end semi 
eee Nittic (Oxidizinge Reagent).....1..+. genieini eal ale a cinatsranal eae ares ft Pyne hy (= 
MR ee UCELC | sles atac sso ¢.0 ie's oie so § soled dg ec '8 ad wae e.sisale a pieaiace ao owe UG 
RR CEL SOL VETIL) iis cc eic akc pease chee: aires ala tagte atv stake arn ak eee trae eno 
Se SEOs, Standa6rd..t.0.5ss> Rd gt gt Are: Oh ee We ee ims ae Gee 282 
ee ETCCIPILAT C) isis ics sees is 00 0 jad up ee stains ay ele Cece er 
hoe me RM VEESL oo stal caus ais Gots) tia Sin ipias Pause astnne ae Ger oNT aca thes eovcssece 69 
MATES (OIN ET) his acc 'ajsla estes sac ne Siva d Wine oe ke elidvew Wein « 4mtrs 70 
Petar ter, Lests for thes. ..ccciccvscccicecasionceemece eaten gaan ead 
Albuminoid Ammonia in Water, Determination of................ Ree toy 280 


Alexanders Method for the Determination of Lead.........22.aceeece++. 142 
Alkalies, see Potassium and Sodium. 


Se ate cmetetta NnaliOn \Ol is aeons a.0c6 oon s. aie sre Woe ee oat 276 
memaurmetry and Acidimetry........sseesss mialetih o Rinbeseinias aie’ picteit ead) it arte tetas 282 
Pivau-solutions, Standard ...:......e4s Sani elia leu stack inate: cuneiohe ese nisin ema 285 
Pomeroe em eternination Of. 6 .-cscs ne es wt os es eons Aa pi Waa soca el abated 181 

os Pam teonstsees, Determination Oley wet, 6 sce dp See 183 

sf ‘< Lead Ores, ie i eae ee an een a eA BORNE IE 184 


444 


INDEX. 


Alumina in Limestones, Clays, etc., Determination Of... ..ccccccccccrecs 


* ‘* Manganese Ores, i ‘foe owes 60 vine ele siete 
ae “* Mattes, . Te ais eile ale aa ptelsee ee 
‘ Natural Phosphates, Ae ss ls aaa vale 
es *- Slags, s bday 5 Sipe avente eee 
oe ‘* Silver Ores, a, ‘6 esep alanis eae 
“4 ‘¢ Water, + ‘Se oege ces ea saan ttee 
Aluminium (Precipitant)......... v0 0 oeees pee0 06s ah oe enea seem ss aie 
ef SA taly SiS cOlC OMIMETCIAl na sek oa eee AAS one ete sie wicheeh 
te  Determifiation ols, van. «es « elben'e windtie ale eee ys saison alee 
as os ‘Sas Alaina ok snes ee oack aioe sone levels 
i se fcas (Phosphate <<. ««. sale errr eS. 
ed in Commercial Aluminium, Determination of....... weiehees oe 
oy Phaspliate,7Composition Of... o... 0. +. seems meee coves 
oe > Lest for (Blowpipe), . 02) sci = sic ate ca eierne aie eee epee 
ss sf * (Qualitative).....sc.e ccvses scan serucness Sein silen emia 
Amalgamating-pat. 2), 05. ss ees eiaie ae wines c. e.A\uteiaus setter vememeneee c's ial aipte italy 
Amalgamation ASSay.. «s/s. %is)s 6 <1 jes sie ole abuse ea aie Re es’ aatater sien 
Ammonia (Precipitant).5 ¢ <i.0% wae a ves side one 5 vie + wanna Sat onetety Meare ove: cae 
a (Solvent) ss.) atccmo en sem cen re kin. sis thew a tela e ata terete ve baie 'te wiahehal Rietees 
é 


ce 


in Water, Determination Of.......ecee6 
Ammonium Acetate (Solvent) 


Carbonate (Precipitant) 


TAGE 
184 
184 
184 
304 


¢ eielaie) 6 Scie e(ele, oes siolene eoccccclicsccesses FL 
- Chloride (Precipitant)........ eb ee secccs esd s «ena oigate nin aterm 
as Nitrate (Oxidizing Reagent)..... o ode wee aoa © we hie Fete aneer enn 
-. Oxalate (Precipitant)....... wate = Site sec cccetee cs au cee sss ghia 
ee Sulphide (Precipitant) 7.3055... 3. ey os « Shae elena Perroryy rit. 7). 
<é he (Solvent) ice ene 00 0 0 tee 0s eles) ee/eleieie Siete salsa ete manne 
= > Test. for (Blow pipe)/: 255. .ceeee oe 6 wet olainiatertte Perey e rn 
Analysis of Bleaching Powder........... eee sscevesees secre eeeeceeees 289 
600 Coaland Cokeis mix vccesches cements oe ered viewiole eva st le tia aannnennm 
as “ Commercial Acetic Acid....... coc cee awes s gee aise eens stent tnnan 
ieee Caustic Potash. 12... 08 6 64.6 nie tis sia bia eieis aia ea ahem 
te eS ef Aluminium iis sces rete coe stam aie oie eos secece veces 20e 
SEP EE GASES Penk a aay oe eer es seeate aoe coe ee tas 8's cain oa eee 
e&°- }** Lead and Copper Slagsiee ances sees oe seccens ects bes eek sa ata 
s ‘* Natural Phosphates...... Ieee eo ek 
oe elt AWW ALCL. wise a a aera ig evn cdeeuens eave ect enue o 5.6 'Stelb isis gal slate eterna 
£5 PST NV DiECS_LEAU y . eeniea pinta waletw stam shawien he ORT PT ik 
Antimony, Determination Of... 0.5 66s. ces oes cine sas nine win aiy wv ¥ 1. ag 
a in Ores containing Iron and Lead, Determination of........... 150 
as ‘* Oxidized Ores, Determination of........ ob a\s ome apy wsi6ls 5 cle were 
a ‘¢ Refined Copper, S $f adie olate ais \ehe d lotteter aaa aretonne «Wet ee 
i ‘* Sulphide Ores, “f Sf eee sh Seem pice: Pag. 2 Le 
af , Test for (Blowpipe)..: .4 00.0. cence = + cae Prise eo; 23 
“ce ce “ec 


Apparatus and Operations... ..ssescecseeeres 


(Qualitative) 0. 0.s<cc0 o 6:0 0 4 ahaha ents aaa ciarereeeiees 


@eeeeve 


INDEX. A4S 


PAGE 

Apparatus for the Determination of Carbonic Acid by Direct Weight...... 117 
te oO ast te “Sulphur by Absorption.....sssesees 95 

ue Cee Rapid Analysis of;Gases......<s00esess os we c eee ar ee 270 
Approximate Analysis of Coal and Coke......... dalMiale oiee'e © shen oielefae'ste 263 
Aqueous Vapor, Table showing the Tension of..... eines eters “IP IS rice ries 355 
SOMME EIEN ice spe o's oc. an sf oie 5 0.00.0: 0 aren ee SC Ie Geese ps ese esp iciess MOG 


PUPSOUICscLICLELMINALION Of... 0s 2ese stews see's seeeseee es poles sisiee os os laiels 144 
rs Seemed Cooper, Determination Of... nc ccseecccccsecvec sess 413 
ee estutor( DIOW Pipe)... 6+ <2... Maine a win care teieie ale Sie ole she ee pinie s'v win opie 23 
eee ( Odalitative). <i... pee a sivibe sie Sins ch 6.6 0's 0100 s1e.o8 6 saa 30 

Assay, Amalgamation....... nhs Bigs Seer caves wreis ela Gin he Wietel F vies aie ate eR OO 
GEOL PSASS DIUNMON., 2.050055 tees Wal stal cga sae sta Aisinisu#iaisate vies eieies alc cee 242 


See cGooner Matte, special Method for. ....:..00sscncccsnevcsseeecs 250 
‘<> Gold and Silver Ores (Crucible)....... Pikale Crore ta sie’ er aren da ote 126 


eee ee SE tt iy SRE COCOPINCALION), cae c osicats coe s Rawlels wae sic 123 
SOS an ss containing Metallic Scales... v.sics +s.0,0.0s1 250 
Ue ne ee Bullion.... eeeseeeoeeeeeeeveee Ge ee ee 20 6 @ee-eeoeeee@eee ee @ © eee @ 246 
46 ‘ 


‘ Silver Bullion by Fire Methodserces ce. BALLON Pk AO ac 236 
i ore fillet Mi f : mesa yelussac Method... ... <1... pie nel Cleiaa'd eh « 240 


ne oe ce ee be Volhard’s SSM ie cine kre ae eeeoeeoeo 8 @ 8 ee 245 
id a Silver Sulphides.... #eeeesee eee eee eee eeoereeeeeeeeveeeeesenene 252 
Assay-ton Weights oe ee ere eve eo ere ees ee eee eee ee eee eseeesereee eS eeee eo 51 


PPP IIGCMVVGIC NES SL ADIC Of. ccs wccre ences cncevesscesocesessecosevcessss 354 


B 


DUMMRCERME MC ietsintele wes cobeeerecvesscescteccvrsstsscccesccseccecesses 51 
Barium, Determination of....... ceie ee vieteyeiew caluaic’> sab cin vps’ ss <ercsis cee von 224 
 CSEMOSMISIOW PIPE) suicics es sv cccecasawcerncescwnrseseenssecess 24 
« MECC IUAMCALIVE). 0. 55 sececcecesseseccceccssisereeseesses 39 
ROTC RUPECCIDUANL Wace s s'vcvc this eset sarecteciespessscsesces 70 
Base Bullion Assay..... Arte Sete: Dares Wstisic'e svs's(oslt' ora ssa s'ers'b¢eiefer ae eSe 
ae Se wampling Of,......: Seas hints Bei ciaels wa tseessevcvcccesecvoe ce Id 


wd ‘¢ Special Method for the Assay of Impure........seseeeees +s 234 
ee CMrA IASG DULNON, J c.sc ec ce cs cass w'nsvcssccecvessens success’ 240 
ee Catia, scsi s e's a ole e400 i cc dicen ties sd vlececseweamecea cscs s os OF 
Pe ALCOA OCA AY 1UX) A ec ccciss sec bodescceseesaseseteccsecosecs OF, 
Bichromate of Potassium (Oxidizing Reagent) .......ccccscccseccessces 75 


Bismuth, Determination of....... ACOSO ORI OL ILIIOL COD COOe ae roby Lee 
caring keaned Copper....... Puisiete scope ereselaale' slain vine ¢elu's 6 6.e'b.e1e'aiete WATS 
SPE SPELCTI LOW DIDE si. ica o's 0 0.00.05 ese ohes oseesals es-ccecneoss oom 24 
ot RET OUIAICALIVG) cca g visor cce 2c snes ss Calne eel eacente selenes cet (40 
Pasnonate of Potassium (Flux)... ...cssecccctcesccsdensecvscesionsecss, 06 
FeRAM carp aciora 6 s.-.0'00 ietdinie isin eisibiels efeie'sia'e'n njeit ee sie s/ap'e't 4 [ese sine ajc 6 ee ROO 


zs ay Substitute oeeeve e@oeeveocoeoeveeeee080 eeoevsee otc eee@neeeneee8 e282 6808 08 68 


446 INDEX. 


PAGE 
Blowpipe Tests... .cccsccccssccsscccscees MPEP re io 
Borax (Flux)in esr. ersrataoe os as eos olegeieeneaae ¢ one e ent 0 66 © 6 elem stele Mee an On 
Boron, Test for (Blowpipe).........+.- were lecelaininy o aiear< te ae spears Petry Pies: 25 
a cy SSO Malitative) A. ons se elece neice ee ca seen < tied Sane 40 
Bromine (Oxidizing Reagent)........ aod Face Bake oan eieeree iverson 15% 
‘© ~—- Reagent in Gas Analysis. ......ccccesescenccrescecs ie pase 
fi Testor (LOW DIPS).a... es sie ela eeaae 6 0 cw a ogee eee IR as 4 25 
Je Sia mUQUAtALIVE) ce = vm «oye 5 she ute oiaee Lin 5 eee ne aie seme 40 
Brunton’s Sampling Apparatus... .....0s..0...00000500) essere ih Pee 
Bunsen’s Method for the Determination of Antimony.......e.eseeeseeees I47 
BuretteS..s ccs sce es bas cise sovncstecveeeesceeace uvele n/iinle iss ees n nanan 
Cc 
Cadmium, Determination of, ............-. oe ne 06 nseielarelbraigieca Vig tee 
‘4 shy ‘© Zinciin Ores,oti. 4 cesaastas ob 000 6 66 sleininaie sie see 
6. Test for (Blowpipe) esc ee ames ce eiele Geen sates elem erin 60 
ee ce (Qualitative) oo a0. cscs os eee nn nee woh ore 40 
Calcium, Determination of...........04. eee es cc cenns whens eds 
os By in ClaySii hose scene seers Wer rr oo 217 
" a | €€ “© Limestone . s+ 0. s 0'sn ee seine oe niente ene oo 215 
de ee | *¢ & Natural Phosphatesi.«\ss6 200m eee 303 
‘ Fs 6648 Ores)... oo ses 0 0be 0, 6 elke a ein ee 217 
ee « 66 66° SlagS. ssa e nae os ean 5 65 aren ates siete ee 218 
ra Oe OW atet iol. ics otis © ole eronne mie pe seeseese oceeee, 275 
«© . Test for (Blowpipe). .. ..00. ses o00 «0s 0s oleae Ay on 26 
fu ce) (Qualitative) aac a aibg ee cee faa at aE 
Calculation of Copper-matte Blast-furnace Charges. .....-+eccscvssccsececs 428 
ss f*- Factors 4 va. ieee eee eae see eneee NS IPRs fines 323 
es €*9 FOPMUN hows a oat @ siacg © vis 6 & 0K) laa on 6, 6 wee 324 
cf “* Percentage Composition from Chemical Formula.......... 321 
“ a Sy from Weight... . 0.004. 6s sna eee ae 321 
“fe ‘* Lead Blast-furnace Charges... <<... ««s.0 s)ecelsianier eee 337 
#6 ** Specific Gravity... 0. cy5 acs oes 0 0 are sane nee a ane 293 
et ‘* the Results of Analysis, Table of Factors for the.......... 357 
a Rae te ‘<*  Tndirect Analysis oo... 2 scene Bp i 331 
“f o3N ve <* the Amalgamation Assays. ..c eee 261 
- By ed se «« "Assay of an Ore containing Metallic Scales 259 
as jee Sis ee tS. Analysis-of Gases. ofan ene 332 
ee I ae ee ee «* Assay of Gold Bullion nas eee 248 
44 Ate Shee. aes “<« _“- Silver Bullion] 244 
“§ ss «* Percentage of Extraction in the Chlorination Assay of 
Gold Ores. 24066 sew ee's yee sek pla eee 257 
6é 6é 66 


Percentage of Extraction in the Chlorination Assay of 
Silver .Orés ia. « Sales Wists WER es 


INDEX. A47 


PAGE 

Calculation of the Strength of the Salt Solution used in the Volumetric As- 
BVO Te SUV CTHPILLIO ftps: e,sraianace vise, cole o's 0 Hisale hes ie oes 242 
Calculations involved in the Use of Volumetric Solutions............ ia ain SAO 
Pear Ofer mOMUM (PTeECIPiLant)....2..ccecscccacscvscosatceveers 71 
He POCA SUGT (DUK). cosy ceo acne eserves Oohnie in etteimicgecr 66 
af RRO AMCE IIS) ce kip cnieile ed eajcia sss e sets pate nas ate saci neteie renire (els 
ae REECE FCCIDILAUIL). ausied cscs misras's wo o0.8 © Sees e kip torwis <1 ap wee eas tke 72 
Carbonic Acid, Determination of ............ Sete die OR ROE Seite: oleae 116 
is «¢ in Natural Phosphates, Determination of .......... sepegelies 301 
a See teTOMTSLOW DIDE)e cic csls ccc ac see cevneneees Acie Gercieraheteus (a8 
“H uy Bees OUALILALIVE) yc ste s.ce'sisiehieces s+ Bilsiciate eis s.eraie sean 4d 
Dee IC ETININALOU OL... acne cc css cers ccceesecevecere Siieain a terete ta LOO 
4 in Coal and Coke, Determination of Fixed....... Seietns elesieieias siete 24 
os pee ooerz.s NMIxture fOr... fis yes csc wens cence a eeue er ee LE 
Carnot’s Method for the Determination of Antimony............ Misia aisteis 148 
yee TOPE oy aI eee Berets ious eters 61 
RARE METI SUIGHESOWDIDE LESLS. ssc. ce cc tres cus ccesveesecenveerue AG PY: 
< a I MESES ale here als ois se ¢ chs. + elec, @in\e © 0 a:-s.aalaya sis ein oe vie 38 
RET ELI) 0r aan ss ou aicce + Me's cieue 8 vo eisic eee iv ec ya sj0n ns 0.0.00 5 68 
rmeeceuorisiast-rurnaces, Calculation Of, ..........cercescsvervevevers 337 
eenigeate Gist otassium (Oxidizing Reagent).........ssecscoveuessncscene 75 
Giioricevet Ammonium (Precipitant)..... 2... .c cee cceescseacases Sera ie: 72 
MRIS IPE CE PECIDILATIL) 7 heist se asc sc slee veledacdsnescddacececicdevc 70 
Se otversinec res, Determination Of... c.csevec ces ccsnseeeececes 254 
RU TIO AGEN yc crz es alaslere ou 0a se 6 vse ius vns\vin'es tives caccene ets 74 
ONIN Neyo ci vein a. eisieicls care a tics 08 sevens pele ces ctesee cee is 289 
Mormeationeassay Of Gold OTes...6... ccc csnccrccncecs ered terse ste as Le 
ne US LVS See ae Pheriee tpie'e' at s,si'5 wise wis" ena e's ele ae oe poeirinial eens". 254 
Chlorine (Oxidizing Reagent).... ........... tac Cera a ge te TEE eR ans 
Mem VallaAblcineDlCAChing-POWCEN. ...05ccecccvwccsecanecenvecenes 289 
eeueime yy ater, Determination Of.......0ceerns stato atietrsts ti eiate te hae 277 
PNET OUI OW PIPE) vs sc cee s nc crce tees cscs oneness ccenisas moateeaes 
ug Demere( Oualitative)...% .. Sie e Wie. 8 ('e sauele Cee HE acis hoc sect. 4I 
Chromium, Determination of.......... Bove staisi sldlerels’s «fence cece naee See 188 
ss Mebestiuri(DlOWPIpe).< 26... 26s» shastoscigva tater 6.4 ieuttaw alel stores ot ais. 6 Nhe PH 
ss MRP QOUATILILALIVE) <5’. i oie ce sees tes Sey pe ARO e Sieve sitet are 41 
STIGUACIONSOIVENL) coke ewe sine sseccs ener ie Deistitiec res JO SGCRSIES Oe 70 
iaseracation of Coals,......2..2cceeras ee buetoi ote tents ae ake ete wisiies ¢ #6 esis ti BOS 
Clays, Determination of Alumina in.........esesee. pVekacanselsisie cise slates LO 
Re ve SPR CCOICTINTI EID wuts wien vistslic ciate ntera’s aie or cacphecectetee ache 217 
“ sh SOM L PON 1 vilecwsiele ee « Pia Wadctet ele! sy vigte ra. tata lsvaltveral natin AL fy, 
€¢ os oe Magnesialina.. ss. Sle istetere as late SO CONG Gr ORCAL ROC 223 
“6 “6 Dorie Atle ters dnc sista a eastetachiew stereo ciereraiersl s ciele cate) eters 84 
Coal, Analysis of..........+. stelpis ciezentie ste myietele Usteorelacelastele einieinitcolecehe wie sce mG 


Cobalt, Determination of........ Sialwls Gus ctwisrel va sie ies a's (ofa anataicis stalls nieces moat 


44 INDEX. 


PAGE 

Cobalt, Test for (Blowpipe)....... pe cescenevecccecces soe se seclnee sian mmm 
HY Xa gM UIALAGL YE 2s ales oe oe 0 nut eens spss 0 05g niewie mis swine teins Tn 
Coke, Analysis of......... sje Stare wYalaie a Sexpieteiegare ole peensenen oss eos 
Colorimetric Determination of oaoae in Iron and Steel... ..,;500s=sesesmeet le 
A af $) COPDELsE wcuthis aa mites Teer ire oe 159 

hd ae “Manganese snc iasstete elias 40 wa els a eelpis ule 200 

4 Me Stel MtaNIMN corse selene Cocca ecceecsevecees 1g0 
Combined Carbon in Iron and Steel, Determination of........ceeeseeees 110 
sf Water, Detérmination of % 77... 5s eee ieee oa Wan 0 @ 6/0 ees 
Combustion, Analysis of Coal and Coke............ oo oe wei ose «annie ana nenag 
Comparison of Scorification and Crucible Assay...-..... sssceee neice 396 
if ‘* Wet and Fire Assays for Gold........... ce ccerevecceeses 309 
Concentrates, Sanipling (of ci .isc ne vinle > ns + ip ict ee eae shins ee oo sas view «minimal 
Concentration: of Oreja ests 100 an as sien ew ac «sa TERTEP PO i ee 


Constituents of Water, Grouping of the. ...... «cs ae essai 4 nalts ean 
Copperi{ Precipitanit) cis ete «sate eta tas ces neew seve eee 6 misuse sie ate eminem 83 


i) Determination oles. eee + biaxe.Ris'ete .svetg tatphen teeeeee 08 <9 elu elegce wien nee 
. Ingots, Satmplingiols sic aceie rate evict a chee ree co oe oh eae a kte re eee 
hy Matte Blast-furnace Charges, The Calculation of.............s6> 428 

ce ‘* , Special Method for the Assay of... ...0sc0.e= «sles sete tees ne en 

ss Analysis. of Refined/s.4). isn = bocce ccererecccseccerccsccesees 4I2 
cs Slags, Analysis of......... vo se 6 ky ow wid gis Web) oie errr ee le, 

ss The Battery Assay ifor.as sau seem sees tanec ew gaa wicten ee tere » 157 

‘* , “ Colorimetric: Determination of......0:..ce16ssene eres yeas 

“« , ‘© Volnmetric Cyanide-assay for..... oo 0 ae00 oie miele alam ciate eee 154 
s ue be Iodide WERE ETE TTT ec 

cy Test for (Blow pipe): «aera ese RPP OT oi. « 'n.4..6 ena: oe sae 27 

“6 sfc) * Se Qualitative) tice. Rae as Live oe eeieie sic ¢ie oes ose aietae sh ttn 
Corrected Assay of Silver Sulphides............ errr rc rrr re 
Crucible-assay Charges, Table Of... .seccscccseveseccscees ce seeceeeceeee [2G 
Crucible’ Furnace... ...-s. ¢ si sie sies seis ¥ivn.ecclas ya Coc cccsercssncecsencouvas nS 
Coiciblesic.. . es siete asa ne ec te cece secre cceccceeencesercccsecessss 59 
Crucible Assays, Losses in........ WEETEPETPT 
Crushing and Pulverizing of Ores, etc... .....0000cesescesovscssscessese 40 
Gapellation \.6. ra. ine ase i cisie's sae os eerie © sewer olga as iaeialn sienna 
h » Loss of Gold and Silver in... «0, ..0.0.0ss5 ssc suse su sninsaiamenaaee 

ee of Base Bullion..... oo ce eccee eves cee mess 0 se sisihlls a sais genome ae 
GCupels wens aie nc tail rele atats eee e ce esence ees cnee siwhisivinn tiniscis enn inmme 61 
Cuprous Chloride (Reagent)....... eve cdeeccccesceds sawebeuaee solarium 
Cyanide of Potassium (Flux). .. 0.0.0. ss00+«+s0+ ese veiw win eieiaie tela salen 
Sees s m0 (Solvent). «<0. .00000 sees s0 sep miataigictgetals tits 


ae Process Tests. . s0ccccse 0 00-0 0.5500.0%0.0 0160 6 bbe clulenieitetl enn 401 


D 


Determination of Alkalies........ ee eee eee eee cc cceeeeee cece eeeeeeee ce 227 
OG A SE in Water. .«0occscs ee ta.ew a clsleinaieinc se ant nnnne 276 


INDEX. 449 


PAGE 

BOPCCTIMIMALION OLA IUMIINIUM 4 2.00 ste ce te ccs vec vcececsescesesctaces ILOl 
“Ammonia in Water. ....c.ccccccevecccce Sado dace.oor eel 
AMNUIMONY..ss.ceccccusece Fi y SCR EDU OSOG ER CEE Oe 147 
BORAT SOTIIC: fee: 5"s'o SARS Ot) DEAS DDE De RCC COCR EOL TICE EE ame © | 
ARI ere ielelwsicts Vika Cielt ee Sint sata vicnecutess SR P| 
“Bismuth..<.. Ce aves tee tien care we tsa Sie aas side seyeiy ets iiiere oy 163 
BOER oe Rec Cag s Sed Ucss Sessa tccs ees cectetecuscees 165 
SRORCICHUINI Et a ccs stg sle.s os -cie¢ 08 6 wictelert oreltaon a eet CTE eH OPC 
POAT sr iiics cise sais ne ccies eb oes ss 9's Beate tiartes tats alse ciel 106 
CEA CIO tein Gattis a wick 0h as 'bcce sewn 6 Siete 54 6 %.0 116 
pecuierine in Water.....-. a RAC AC UR OTe ites ce ga SED 
Me ATUL i eielic 9 divs Woks svc po ce nese © Mais etae’s stele ose 188 
ROMS UMC Te lected s Gabe vcs se sse cose s PITA ARR Pecewne bap 
POCO DCL dacls cielna cr er alin se velscenees meer chesiehele’d ee aaverer stare 1s 154 
er eweuMearponin Coal and Coke... s0.cseccsce ces sucess 264 
‘* Fluorine in Natural Phosphates....... seieter es Sec nobenocd eek 
RIE Ae OU VOLS ne a dis ries owas vole eee ercacle eee ens eye BEL: 
Jee in Base: Gullion........ iain: svsiaca eencste ate 232 
eR ce CODDET Malle. i csies ce pees Cente ceas 250 
ee eee Gold Bullion... f.ccs cae Gareleciee ZAG 
Serge 6 85 DM LOS OIA US) ClC on oc s'nie ccame ai cele cee 122 
eee fe Silver: Bullion.... 3 +. «2s MPT OER CA! 
eee een Fo LVer-SUlphides, .. 6. c.scss secre cedse 252 
GLO et. s « cpa CARRIO Bet CICS a ARR IEOR PR eaaee 168 
CE WERE fia eteidcfols a ad sinless Weree's.9 of sre tse sinus s eeees ee sis 136 
> Mapnesia§.....-%: Bre viaters aia <0 siete siete e sate © cialis diaih os eleiels 220 
DOPVIGROANGSE. 5-12 bee eos .s HO EE, Sie Titel sais Sannin 194 
BCI See Ore ls how se sivie'ela vida sielw tins Riasely sei doslcecstts 134 
RIN CC state a er clefts + sald sldm'e'y ap ss a aes ceases “et oie 11g 
eer te es he Pass oar Ty ose a 6-9 a 0'e Sao doe pe iss €e ee ola 211 
BES LE SUNG NV ALOT! seeks cis senses wv sdec sees 0 ater OO 
Rene MIPIM NA ALLCEI IN VVALET 0 gre siw sions v's stare asa voces Cees ce 277 
Fe “ angsv olatile: Matterin» Water... . cscs. ss vce 274 
RSET eee Salat aid sts ete ch a were nereue sie os isi Scie © sets ae ee ol be 
OSLO IES TM Maye a ian iets ore ne ae rag ei bere aag ea ge 2 227 
BME les LOE US fir Soivhare la vate evs aa a'a Giele's’ stale a? otp w acas “sy Shee 100 
‘« Pyrites and Gypsum in Coal and Coke boss een gh Bor ois eee 265 
eS Pe TIS Is cus sy eh ie tive nie wisest cece Saicus vin Gaines i 6 414 
BS Cea MOP SLIICONs fs. 6's... 1 ied ceu's Oh ceca wel oe a eéas ai 
RUA et ae es ia's "soo cic le yma ee tele tis Shek vive aime aes ate Paneie ee, 
BOR CAG eTAV ISIS 7 os 's0 selva gals Gs iow bivte ecoiecssid'er es areheneins ie 293 
‘specific Gravity ofCoaland Coke........+...0: Dh ee nan 266 
RAEN MET s AN ae an stclac hate wivicls shcie p's oecwie gfe 40e AA one 
pees Ott rie. ACI im” Water cc s ccc cies p «)ne ol s'e' oe o's COO, Se 277 


** the Heating Power of Coal and Coke......... Rs Roa 266 


450 INDEX. 


PAGE 

Determination Of Telluriut., 453 6a6ss0ts covneced¢ecceos @ ernie ee 414 
oS Nal rt anacanein tes Cu nase sere ee a TELeree rye re re de Se I51 

is OS TALSTIATTIVA Sih nnaie teas are la aa Ramee’ sco-a ye, ee ccc eees ose seely ano 

of “Total Solids in Water... oisss soe 5 00m ely tie eens eet 

$4 “ Volatile Matter.in Coal... 5. <0. 2.50 segs salient 

os RN ALCL a view Ca catiie RE. oh wake este ce sale 5: ait eae Siew oe 119 

ce EMC TA Canieteresatns Loeee 0.00, 88 ck Se lsia, oy. a) 6.004 9/8 ve ee 205 
Drown on the Determination of Phosphorus in Iron and Steei AAP a eS 


Drown’s Method for the Separation of Iron and Alumina,.......seeeeee+ 185 


E 

Eggerz’s Method for the Determination of Combined Carbon in Iron and 
HEEL yin cas dw sien a ele lat etlen a tk so 49 ce 0 ive esate ons s CoE 
Eggerz’s Method for the Determination of Graphite in Iron and Steel..... 109 
Eggerz’s Mixture for Carbon Standards:’. .....:...). 2s e)eeiee eee 114 
Electrolytic Determination of Copper.......... rere AE PPI IS © 2.6 eee 
if - ee Oxo PERE I sem 187 
ss ns * Nickel and Cobalt... 32.07 as wanna 213 
s Precipitation of Various Metals, Table showing the........... 358 
& Separation of Iron and: Alumina!..4.. 1s. eee ri tke 
Elementary Analysis pf Coal and Coke...........-sss000ne6 oo.s 00s wee se emg 
Elliott’s Apparatus for the Rapid Analysis of Gases..... Cree sevonceosens 270 
‘« Method for the Determination of Total Carbon.......... os aisle ees 106 
eS a f* * Volumetric Determination of Sulphur........... - | OF 
Emmerton’s Method for the Volumetric Determination of Phosphorus..... 100 
Equation, The Writing of Chemical... .. 2... 5 va. keels ee » 312 
Examination of Ores and Metallurgical Products Preliminary to Assaying. 21 
Extraction of Gold, Determination of the Percentage of the...... ene vaca ee acy 

F 

Fahlberg-Iles Method for the Determination of Sulphur.......seseeseeess 88 
Factors, Calculation of... 5. ss01 65 veces soem + oie nen ones 323 
‘¢ for the Calculation of Results, Table Of feces ene ois sins area late 357 
Filtration. .0..)6 0.0 cenies sis py sie oasis ee shee sls ines pis 2p Vie etait & enon o MOE 
Filter-papere....c els csrsels steers Cle bes sing 6s Wa Seta ent eee seeseeee 62-87 
Filter-puim pica» c.c'e.o et wanes cen rola op tele ee eA. Pree ir .62 
Fire-assay for Gold and Silver Ores (Crucible)....... os a atte ciare nate ote akan 
ae eS his hid ‘¢  (Scoxification) .;, .:...ae ee «a hte Me ieee 
ef MY Platinum AUER PRE 8 ee MC ST At ohh see d tial alotigiarats 31la 
“ “ the Determination of Bismuth....... cc on aan eee eiend veeemne 164 
vy as a *@ad pret ces 00» ame are Py emia ake o's take 
Ss Shodan iS *€ Sulphur. 2. 0s sicgureeameernewnn : gI 
fs Seats am Tinks 2 4 i's a mete eee sees 152 


INDEX. 4g1 


PAGE 

PM UO TMIVETIDUIIION «55 cy ssa ccsceccesnst ss cedesdsescessecvesnss 235 
Pipeeassaving. Fixes vised in..)..... 020. sescee cceccecsecsssccccecssess 07 
Fixed Carbon in Coal and Coke, Determination of......,...eceeeeee- Saren 204 
OS SINE RS ane a 2 a RR Sad CURSES Ie: A. Oar rSCEN CeCe eRe 63 
PeGUSe A OSUROIIE Of... 0.6 scenes oa sees ses teeee Mieipieere la #¢ e144 © nape vee ane 
Fluorine in Natural Phosphates, Determination of........... ie sleet og utarant 305 
MELO SPELT Nie 6c ois se, ciris os cee ss, 0'6 9s nt ivecinne § AOS IO POI ITE 28 
Fluxes used in Fire-assaying........cccscccees Pelersis sisi aretele sdtere,s shies Pept Sei, 
REE V CLUASSAVING, ccs cere spect scdeececsa visas aidisy soja stereo 
Ford’s Method for the Determination of Manganese.............. cetaerene 194 
eI ATIGIIG OL © oe oie do oes ks a nies vis ode woes cisco sees iyey 
ow for the Calculation of Lead Blast-furnace Charges............. 342 

i ‘« «© Conversion of Degrees Baumé into Specific Gravity..... 296 
Pee mimoniain Water, Determination of........cccesesvcsecsonscsees 279 
Se ee GiA ees vires es ws PR ET Acie arsce si niais aie cisih sia siedie's 6% ete vietets 61 
er aE ety gist isis cnls o sora v eas $035 00d ee ese eee e ene Leute 54 
Preoeere sw ererimination Of AlUMiINa in... .scccsevcsewercccteccesiossees 184 
es he ad PMO CATEISIAItl i aitietatsiieie tisres stone stele inshe's @ 5s. 000 < © 218 

. Pn - CCARSTNERST DORAN s TG gg ea BA rash eI ae 180 

a he ae BePVU IS AM OSC UIE ca callers a's elas e cid are moa AP Ae arr 204 

=f eee ae pee TLC OAT tena 'eix ce cea, a a cheta carer whois Gaal sla ee teenies eet 84 

a a oat pe UP OSI) glatale ic laiates\civia sas sts eae ie.n nines oia's' sie el 
pe tg, © Ye ME LUC A ieries «aie ee sela cielo deie.es Fe ete sb s.es eae ee ZL 


G 
Gas Analysis, Calculation of the Results OU Meas Ce etitrecie tester esse st 356 
ee SIMO ieee hr ce se vee ccc cenes snes ene ece sect ts eed cevses) 200 
«« , Determination of the Specific Gravity.of... .'.... Sicthiateissietaleucals vale aleuveOd) 
us ’ ‘The Density and Weight of One Litre of Various...........+00:+2+ 356 
Gay-Lussac’s Method for the Assay of Silver Bullion..............00202+ 240 
eT, ASSAY Of. ./..5 02 ese sc ee sc sess Sect a clodisiv's susisiss sible tin sie trie ced O 
ad Peet tech OL LMpurities ino...» ssi Panties RR OREO TOT Ne i 
tg iemeaioss.ia the Assay of. .....ess0 fia clsia Awl einicje-etealeve erate ale cea age 400 
os «¢ , Melting and Refining Dir uch ones iim ien eisai’ oh syiete ciate Easel ta ta Te 
Sea OIDM NS Of 6 ois se ss wa eln oe big eYa aia) a toate ate a ia 'sfs/ pista. ¢ cole dee 450 
BM OLELUMENALION OL: . face sce sca wecccee wivisieisieiaraie ota ins eislais @ ait tec, 3 wa kee 
“ My Peat tsAS Gs OULLON vec crs vinala cle uve sisiaiatetia ses s\sieue scone S 4 
a es ee cCopper. Mattes. . 3.0.0 SMO ere Pipe ee wietctaia teats 250 
g re Dn ONT OS hiv ald ein sts .cecdie ate o 8 S07 508 Se erececs bv eae t 122 
Es ae ee Silver: Bullion... ss. « be smiles Raatees piatalarsteas @ etecst + 240 
Ge pedsOSS 1) the Fire-assay for... ..cc cess ccccctesccssesccesececeseseee 300 
*¢ Ores, Amaigamation-assay Of........0eeeeeee Pdacsir ee f oR ds scr e cOD 
Es am eleecnanical ASSay Off. see gras ven cedaes eiehsld sive idee emt even 
as ac nrorination | “86! “cookie c swiss wa's Deets aoa hs aialt odiais 6 Sat neon 


fe *¢ containing Metallic Scales, Assay Of...secccssecccessesseces 258 


452 INDEX. 


PAGE 
Gold, The Preparation of Pures... .scsccu0es 6000 0es.0 00.0 « eeielaninate meen 
Graphite in Iron and Steel, Determination of. .....0.s eee ees len ete e eenneane 
Grouping of the Constituents of Water........ cee ectese cone acne saeelnaeem 
Gypsum in Coal and Coke, Determination Of........ccccsccccccssvcccces 209 


H 


Hand Sampling... 06 cde seccceccce tic se cues see 60 ese eicleie eiteennenn nam ¢ 
Handy’s Method for the Volumetric Determination of Phosphorus........ 103 


Heating Apparatus. csi. 'eley says 5 0s v0 «0s oe ce os otis aie te oy 

*s Power of Coal Coke, Deraiavies Of 5 os alae stent aes aces e208 

Hunt’s Remarks on the Colorimetric Determination of Manganese........ 207 
Hunt’s Remarks on the Determination of Combined Carbon in Iron and 

SSEGOL vials s aleve siete a's a tice ye ebe alte rear ntal eee Prrer ee ar Ilj 

Hydrates of Potassium and Sodium (Fluxes)... ..... o a 6.n's aie) inl ed 5 nee 

a i x uy - (Precipitants)...... “lpia th abere 0 i's: nide Ones rn mea ae 

Hydric Sulphide (Precipitant)............. on te sn on oan a eo eis eite ian satan ann 

cs ‘¢ (Reducing Reagent)...... WOME VET RTT de 

Hydrochloric Acid (Solvent).......... MPIC ra te mores sone i oe hie os eeeene 

Hydrodisodic Phosphate (Precipitant)....... os eajetala:<etalamienememe » eee aoe eee 70 

Hydrofluoric Acid (Reagent).........e.008 ahaa a aeerahens gels s ts @ siece sen 67 

Hydrogen Peroxide (Oxidizing Reagent)..... PEE ory er Sone 

Hyposulphite of Sodium (Solvent)...... els covnesss 00ew eee ule sulete ainacitectnnne 

I 

Iles’ Method for the Determination of Sulphur.......cccccccessevesesess 89 

Impurities;in.Gold Bullion... .c.wmasteas star cee ee ee oan se eek 606.5 eee 

UNGICAtOLS.. oa bs ee so Sieigte'e ee bw wie a wigik ee’ at Shen ami aTaye a ne Pier 

“ used in Acidimetry and Alkalimetry......... 0 5 oop iyo ee os = eons 

Indirect Analyses, Calculation of the Results of..... PP it eo Pe et 

Jodine; Test for-(Blowpipe)<.5 0.406 se oem b wicdelacyls eee bore Peer es rt: 

Tron: (Flux) sce ih eins a oa ale oe errr toma a tee ene os sb Sater <pae wee «eas aie ee 

‘* and Alumina in Water, Determination of........... «owes 0.00n see nee 

‘o5, Detefmination: Of ..G. cnn cn teeta tsar eceee PRI ek cei voj0 a cig ee 

** Electrolytic Determination of... i. 52... 20.5 «ee vee eee 187 

‘* in Arsenical and Antimonial Ores and Mattes, Determination of..... 180 

‘s’ '*Clays, Determination Of-. <5 02 sim seins ss eit ene ee -aiate Gob ea ee i dy, 

‘<< “ Commercial Alumiinum, Determination of.............-.00. vese 299 

«6 « Fused Ores, Determination of........+e0% MITeT rr ae 

se Tron Ores, Determination of. 2.1.45 .5 see 0 = 6a no 6 wre leip] wel elatien 

«© Lead and Copper Ores, Determination of....... sie. 0 6) sia 9) kin eiaiee ence 

«« “ Limestone, Determination of........ santas 2 0/n a0 sige whe w0 a tete alee ee 

4¢- «Manganese Orés, Determination of,,.......) sass ae 177 


«6 * Mattes, Determination of....).. o..enn vee Gee MO vo 177 


INDEX. 453 


BAGE 
Iron, in Natural Phosphates, Determination of........cssssccccccccesess 304 
“« « Pig-iron, Steel, etc., ef PAcdinewuaeistee ts a6 ee ree eet loo 
** “© Refined Copper, Ze: Eee ietas s Wikee «tiv cs bcee.e telah AL 
‘¢ =** Silver and Gold Ores, ‘ Sa iatet sist tay stelwe iste ¢ e'egloe cig B7O 
Res RE OCLEL IN TIALION OL... see's cideece cee ecccccsesuscsesvedecese 178 
“« ~“ Sulphides, Determination of....... Mele eae ciate sisiwid es sibs av ve Ves & oid) 1 TF 
Sema i itanierous Ores, Determination Of, 2.0.0 -ccssersoscesceseseves 193 
** Ores, Determination of Alumina in.............cccccccces ate wees ce LO 
Ae + fs “ Chromium ins). ..< Seay hula «ie Stel flew ie ce sahal te 188 
sl ee = Pee TOU TOY aa cs ote vies Ceield See eee ae ioe ceteris ae btG 
ss ss af Sa ieee PLATT IICLOUS eiiciee elecis cov n.e ele se essa 193 
a fs as ‘* Phosphorus in...... Sia'e'e Winds wien ecaia'y e/a eld/a:a! « 100 
ae ee as ePOUICAIG wes cas os Side vis s/o nlcuavamiblereslietern@iasa elt hey 
Iron Ores, Determination of Silica in Titaniferous........... rapete ive rene aks 192 
e 4 4) MmSELIPSLVLL Da Ti acyr ate sok age taal sate at vistas «ie ate A Cpe 88 
BPD TOTO D Thee ae cic kes isiecc's etc cdses secs ecu enes posteces De oe 14 
BePELESU LOL (ISIOWDIDE) cess cccerscccecess die EN Ie By Oe here el 


es S¢ te Renee eG reer or tere end ose sie ti cad esa cae 6's suis ees abe aelee 42 


J 


Jig, The Vezin Laboratory... see. @eeeeevoeeaeseeeeveeeeeaeeteeveeseevee eee 8 8 @ 421 
Johnson’s Method for the Writing of Chemical Equations......ssseseseee 316 


K 


Knight’s Method for the Volumetric Determination of Lead.........s000+ 139 


L 


Lead (Flux)..... ME eite siacicleisacs sve ale sioe'e ces sade t cae aeuewsst io se oe'ey 209 
eA Precipitant)....... Ay eee Ait Pe oe Cite Ret OsIe a ee ay K 
“¢ Comparison of Methods for the Determination Of ..........0...00- 136 
ETO TIGL OTOL. tice nna lnc sooo tae cots cee be Bes ececebeeanvaes npeaen es: 
4° ie BODY Fire-assay cis. ss vv.cscyas racy veins ner viceeace siete 137 
Meee SL uiratmin ois is. ry yO EG SES cele ageseaterats Reieineteie hs mito wivit ales OF 
** Gravimetric Determination of (as Sulphate).........4. Aste SE Tet te 
i ‘s iS “* (as Metallic Lead)..... ene ine sist l so 
*¢ in Refined Copper, Determination of....... Sieee eee acpi tears slteace ee aie 
‘“* Ores, Determination of Alumina in...........e0% ofa he acess Mereidie au 184 
as 56 ae ee Calcilim it. oc Aasce «ee releases Maida mic Miacsgleex enol 2 
s &¢ sf SEO TPON Ati ste e a0 POE Cry ME eC ree ew ie) 
4 Ks Nd Magnesia in. ...nesesess Risteteieieitisie ae niece wR ees 
a a * F© Manganese ins. cscesscecessscevecccecesse 198 
. a e EAST UC Na bales ene Mintel ace ien o4bie fia) ewan ae eeeueres 79 


ss «6 s¢ AS Sulphur im. .....cccveccccesccasicccssrence go 


454 INDEX. 


PAGE 


Lead Slags, Analysis Of.:....0.cscsrcbonevceesebbectoe be ves ak MER Nt 307 
*. Test. for (Blowpipe)...s.s0ccrssescsesesscod avts op viv webrelih pian ete imme 


Sgaw ieee rot Quantative)’, ..ne iss orsiai ein ce oie eietatebate ane sae ve Pe oar 
Lead, The Volumetric Determination with Potassium Ferrocyanide Solution 

Olin nity pease be piess oes 0.0 pb.cciee es cles y sm ah dip hale le pinnnt sin 139 
Lead, The Volumetric Determination with Potassium Permanganate Solu- 

TION) OL 6s Seale a tists estes a Ge inzed ob to VOsiy. wal lets eee ena sou enw B Vet elia 139 

Lead, The Volumetric Determination with Molybdate Solution of..... «Cue age 

Lime, see Calcium. 

Limestone, Determination of Alumina in......ccceeseceres eile Wesse cca 

id pe © Calciuml in, eissss sree eee vietisteleals 05s ae 

s fi Ae Tronian. ths 05% na eee rere eer oo 

ef fs ‘* Magnesia in..... Wer reo 

ne a fe ICA AN. ys es oe p bn 5 atu NN aieS MESue Rey! 

Litharge (Flux)..... s wolpe bejeis able lotesin niet © «4 50s oars ene $i 6.002 a ee cee 

‘a, ASSAY. Of; hus sien aati aire Grolata'y sis ie ole cco se esbe cet aes We hi Nm 

Lithium, Test for (Blowpipe)..... PPT os 

“ t4 So ( Qualitative) s .accdene BRT a eg biawlca abate hee vs weeiniens 43 

Losses of Gold and Silver in Fire-assaying.......... Shee otis cas 386 

Low’s Apparatus for the Electrolytic Determination of Copper........... 159 

«« “Method for the Determination of Copper........ sec cceccescevecee 154° 

‘f ss BEL id “ ** Manganese .. 22s: sence bien sie Xela 


M 


Magnesia, Determination of...... Sop AGs coc ee uses bcneccae See sips snaeaiieeee 
2 in Clays, Determination of........... re erie 
se ‘* Limestone ¢ OS Ee wee ie hc ea ere rer es 
zs ‘* Natural Phosphates, Determination of............e.eee+e+s 304 
ss ‘* Ores, Determination of... ...:.... case eos Shaeawee 2 5 kOS 
aT Ete OAS: i, D \lstne eux ealecaiele siete coe ccene coos ay ewe ee eae 
ne ‘* Water, es METTTETEVEY CTT T 08 co 
de Mixture (Precipitant)..°... 202.0000. sss 0s sipime mies cats seen 

Magnesium, Test for (Blowpipe)...... 0.0 ss00ss00ss ase ei eniislen nate nnenan 

S see (Oualitativeyge. cee. sca aie Wiete tems vec be cess eu ee oma e 

Manganese, Determination of........ ere kee oe 0 ote nan p snes wines 
“ by Ford’s Method, Determination of....... i000. sana seneeen 194 
“ ‘* Low’s Method, = “Foe o8e wenis © ve bis a aiete at mene 
ihe ** Volhard’s Method, «fe hee's 4.06 5's Srelata sty eee 198 
v4 ‘* Williams’ e e MERETTERN Cr wri i 
4 in Ores, Determination of........ 54.5. «00 ssrsn ew sinesien anna 
<6 ‘* Tron and Steel, Determination Of... .... ..5.0 s+ eles sens 
<¢ ** Slags, Determination of.,........+. os sssiies ates ane 
“s Ores, Determination of Alumina in... 0.2.0. .0us seemen ee 


Ss fs ss ** Tron in. <.e+t saute @eeeeeeeeeeee viv] 


INDEX. 455 


PAGE 
Paganesc Ores, Determination of Silica ini. .....cccscceveseneseaeeess 77 
oh , Test for (Blowpipe)..... Siechecttatts ofasietsit ¢ One ee ra ON 31 
ie gee (OUalitative)....t..<. Bars cl Pi inteeia a ak sins tia alee a sisreis eit 43 
Marguerite’s Method for the Volumetric Determination of Iron........... 169 
Mattes, Determination of Alumina in............. Se dinlactevions calce ee aon! 
os 2 MRSA Tate tiem pat as ec aye dec ee We AACR OES et yy 
hi * MOTE TRE ela rd eld gs in de oe ae ri ey A ea 84 
Measures and Weights, Table of........ A Dac WA Pie 2 RIO 353 
M@ecnanical Assay of Ores ........0000 By EE OTIC ERR OC Wy 
ena ere CS Old) BulliOnis. 6 ciec.s sieves osc yee e see's see cas evlies ses 371 
Meee PeCePIIPALION Of). cys cic ws cine es cs ec ene cue eesess coevens areas 133 
BEC ETMLOT HOW PDIDC) 5.0. 5c avin siege sens cre ceveescdicccadeesteas 32 
rs a Be eA LILCLNG NEM osu eye vis ee Gsie elec cs) a viele a/c tye ere @raed's os 43 
PT PCAOB ETOCUCTS sOAINPIIOG Of. 5. ccs cneccccsncscccccesscrsoccs 14 
Metals, The Characteristic Properties of....... mcals Nate: ae ule d/o et « CORO SE 
a Pe icectrolytic Precipitation of,......<.. Seals aie aien oun ate a ele ciecie se 950 
Durem Determination Of... 2.0... 5 ccc ces eens scesecececs mecnceesqes LIQ 
5: in Coal and Coke, Determination of............. AA cicatate it 263 
ie ‘* Natural Phosphates, ‘‘ Bee Seksty ierare oe2 Wierslcefeinists sistas sora 300 
ME ee IONICLEECIDILANL) 60 5. 5c cic cse won secs eb gsais (Sespseees mae 71 
Molybdenum, Test for (Blowpipe)..... ate eh ae re ee eis stepiaiats Aba Neh CEST 
a Mie MOUALILATIVE).,0 ose oss «aces ns ee cabs: ascivia cle cama st 
Moulds used in Assaying..... Bie sitvee © ce oie oro ace ain Mh Reecsarh ola iatereo ele cust «50 
Mases, Listof Blowpipe Tests by Prof. A. J....cccessecsvcceces Asche sa OTe. 
Muffle Furnace for Coke and Charcoal........ AS ore nS an Ceino oon Cy, 
ee a EMEC CGAL 5 c0c on avs 0 5's LAB An RODD Core Oe OE res ea 
N 
Nickel, Determination of..... airy sistas clas see se sine os. Gh em eieletieele Casale 
*¢ , Test for (Blowpipe)..... AAS P eisiésics sine tiles ebelcnceswuevers 00 Sm 
mee CuAliCAtive).. 624. eels o'as gin iptanieliela le sueletaeratets acer aivatsie/eia's & Saeed 
Patrateror Ammonium (Oxidizing Reagent)... .ccsconscsrsccccccsssceases 75 
ne eT VEteCTeCipitant)....0cis0c20e Mie gies thot Satraimertne icles ws cele SE 
7p OS i OO 9 a era atioeeletes SR whe he tects lye 
a ‘* Soda (Oxidizing Reagent)...... areielatcier a tiahe aie aie me erat ie aly sin Stemeneee 
Peerateavinuyvater, Determination Of... .spcsccesiccessecscscs sisitiele cronies ce 2OO 
cn (LO eS a yates LIN IC SAP REOR Pee s: 
Mitric Acid (Oxidizing Reagent). ....+sceccesveccccses Save Seslalapnieccecsialene 1a 
oe ESRC SOLVENL) i... . > Be velerivis ss. cols wivaleeleelartceieisen bese steigee s bass a? LCG 
¢ SPR CEUMOFCESIOW DINE) .s.30 seicesisiinis sisececris tnnecess septs cscs suits 
46 ‘< Geer OUALILALIVE)c.. cc crc ctnssereesesaesegecsceseeesns | Ae 
O 


Operations and Apparatus ......ccccceseceves coscccccscccccccccccscce 4G) 
Ores, Sampling of oee@e 9888 e@oevoev ev eee vese2 8292 88S CH RSC Ge RF FH HR S988 @ eere 8808 6 


At6 INDEX. 


PAGE 

Organic and Volatile Matter in Water, Determination Of......+esceeeee++ 274 
$s Matter in Natural Phosphates, ‘¥ MEI Ry ne 
Oxalate of Ammonium (Precipitant).. .......... #00 0.6 0.6 6 8 e:o/mie Mpreleher aac ean 
Oxalic Acid (Reagent) ature st, secs so oven vais 00 0 vie ep ep.s ols mv vie b sisiee ae 
Oxidizing Keagents..ccacas «6 esc s oss am wieie alpieted «) gluta Maman id ghecala are te 74 
Cxupen (Oxidizing (Reagent)... 1.1. cc clsjesl, «oles abeeinany eens date mis eolnn aianort 


‘¢ consumed by Organic Matter in Water... ..1.+sssshewalees sienna 
‘sin Refined Copper, Determination of. ....s.ess sususseuuevan cnn 


P 
Pan for the Amalgamation Assay......... WREPTERE YO 
Parting Buttons from the Assay of Base Bullion.............. eons ecls s wee ae 
Se eAFOId and SUVErMsOttORS.. stds eects « ote semen 0 ciwiale’ pin eee ene 131 
ss te “BOLLION Si. tie anid ose a ti. Sune, dae eases Senco EEE tog asals one ree 
Pearce’s Method for the Determination of Arsenic......... er es 144 
Peeny’s Method for the Volumetric Determination of Iron.,.............. 173 
Percentage, Calculation Of... Jose 2 ces cts st sive ng ses eee ey cele eee 321 
ti of Extraction, Determination of....... £9 0 Ws eevee PRP OF 404 
Permanganate of Potassium (Precipitant)......... 40a chaeedee er 
i65 cS 3 (Oxidizing Reagent)......- ys 2 eau abaneage oneranee 75 
“« “Test for Organic Matter:'in Water .: cccsesee sigue: en 
Peroxide of Hydrogen (Oxidizing Reagent)... .......-s0sseares sees tne ve 
Phosphate, Hydrodisodic (Precipitant)....... PR ey ihe! hee $e eet 
Phosphates, Analysis of Natural... 0. . .0. J c.c0 ess canipn 0.80 9) spay seals ae eee 300 
Phosphoric Acid in Natural Phosphates, Determination of....... capes 301 
Phosphorus, Determination of/; 30: cs)s¢s)+0s sie asics oe ied eee Too 
& , Lestfor {Blowpipe) <7 o< steseesaiarcnies erie. Oigkh.< sate eee 33 
ay “fl *e( Oualitative) wea seer. 00 000 0s 600 0 a atnig aitesng me rage 
Pig-iron, Determination of Chromium 1in...... .. cere erocerecereverese I8Q 
3 oes ‘ ‘. Combined-Carbon:in...... ...esee eee Sida winh ie 
tel «6 ** Graphiferiniss aaeden tele 0 ale a egal secre sseese 109 
AL wate “6 »*€ Troms ittes's os'cls wees te ae x tie eene nee soos tod 
su Se an nest ‘* Phosphorus ini... 00. sce vole eter A 100 
se 6 #6 ** SilicontinsswWes a0 0 oe ete eee one osc om 
re Nese $ ** Sulphur 1n.......seeeeee a's dates seen ene cave O04 
Lite eenst ‘© Total -Carbon int... .../.. 0.5 4c ane 106 
Pipettes. :: CS Lb SesERE DEC OREM EEN eee ris Vin terete fe slesigem so enoewesenseede Og 
Platinum Grucibles: :1 22150. See. neues aoe semen oa 5 sure daa ee eee eens CeO 
‘«.. | Determination of, in Ores and Alloys............ re cna ehe os te ETERS 
Porcelain:Crucibles.:..s sae hs vba avn ass Seen ces on cele e ones 60 
Potash, Analysis of Commercials 4124.0 0s0:s00005 0004 oon oes se acnvaieten 287 
Potassium and Sodium, Direct Determination of.......... teslecavew ens y gemeg 
e “e -€ - Indirect id he a 0 + 06 ele nae thy wie serene ee 
* ,, 9 Determination of, .. 2522.05 +000000s eee vs sislsneeereentnen +° 227 


INDEX. Ng oe 


PAGE 
Mermeorieeiicuromeate (REAPENL) .....e.asccbesesescocccccsesscscoessis 95 
4 Bisa phate (Flux) 200.5 46s © ies Rint ee ieieha aierais as cte u's s alvie'csrs/ sie vicivis ey OG 
ae eerie UX) os ass 44 aoe ons ee he % TNCs tv nee. See 6 web ee OO 
as Ginerre (Oxidizing Reagent) ic: 1.0 st eess se eees Pastels pisses 75 
ited VOT Ge (PIMEJo. ac tc ese sees edie fe teense & 6% we winks Bice sla didlo’ sis 68 
s% i! POOLVCIIt). sare Datiistatteremnblateleetvicross ste e ess 6s ecie's ius hx 70 
Ai Be eet LOK ies eaicle eine olole's iso cie ex's © 0) miele /a’e'w ev pise ofdve's tice 67 
eS - PEPeCl DI CaAit ) te iisie tes sie ose si are oe aie) a/e't «0.5% rears otacete a2 
sé ss Ul Cater G1 Cras i 1Al YSIS) Sv is oss cv ne 6 0c’ cnise ci0 enerneve ia 
ee Permanganate (Oxidizing Reagent).......... dy ink ghar th ae PRR er Se iS 
ee ig (Précipitant) {.-45.< Sietetere vere tie eteleietice Sie alse 6 se ops 
ee Pyrogallate (Reagent in Gas Analysis)...... mutants taiaista! init ees 272 

af Me UMOGTRELOW DINE) o< scr os sce sues 0s cc cen eed c's ee tie ate hereto Oe 
re eee COUalifative)., css. 0 cee cse es Cater o cuitee Fe eecccke « 45 
PEP OIOIATIOG gente y o,0s oles veo e's AAA Btn Oh CLE AOE Pa Oe OOS Wale Ce isies ace 7 
Precipitates, Table showing the Properties of.........c..seceeees Vistaate cee gO 
Preliminary Assay of Silver Bullion....... Abi ea OP Fee ciatnis 257 
a Examination of Ores and Metallurgical Products............. 21 
ie oaraton of rare Gold and Silver... ... 002... cecee ce wcccseveecserns 302 
Prootin the Assay of Silver Bullion...............000. Ss wisee's afer elacn hy 2 5o 
Properties of Metals, Table of the........... Mata cisfals wialeisiais/ateeialatsc/sicisteceite 09 5U 
UST Ie a A is pateneraia’ ai'ete Selsiss sevice rive sseup eeir'y sc) 40 


Pyrites in Coal and Coke, Determination APA aTENS Sa Ged ee 265 


Q 


Qualitative SUMERECGUIT Ut a dis cis ais cicte’s bintess v0 ek Gulaee ses 6 ee0'se 6c seeeesese cs 38 


PP EMIS Es ssleicin cies esse esteacsererseceseie Diet d0.0 pee 6 60 6.6 66 6a 4144.06 © 0's.) OO 

ne fecddmtnc mapia Analysis of Gases.....sccccscoccescscesssas 272 
Reed on Ore Sampling..... Bia) e ccerekciete ar hie aoe BISieie mid oe baie ste oo tities Caeel atten 14 
Refined Copper, Analysis of...... Silene cate ahalainifous biota ie aiata a ateietoie ince Mr pee ee: 


Refining Gold PePIIOIIEN ils cclsics ce v iinde's' a oi a0 eblicet oreo tose re aie 374 
PGT AEST DE, o o.cecice vo ccses secs cecciegescseebenccvscceses ceses 424 


coset eoeseee eee @e@eeeeoeree vee ees Ge r%¥e Bxve see eeeo ov eee eteoneeeseeevnet eevee 51 


Rose Crucible eeece eee e @eeteeoereeeeeee ee ee eee eee eee eset eveneeeeeasnveeess 60 
Rose’s Method for the Determination of Bismuth...........0.eeeceeese++ 163 


66 


sf af vig £¢ <f Lift gnics Se eae etietee cna Iéti 


Ss 


MET fon Toh ds 6 ot csecsda cis caceececvens os dnes ateeoe 68 
‘* Solution in the Volumetric Assay for Silver... ..ccescecscsesesseses 240 
Bamroungiay tiand (Ores): 0% 006 ot ciwemnsies nepal tesa wc iete quntereis sind siaratvinn eS 


6é 


Combined Hand and Mechanical (Ores)... cccescocccevceseccsns 7 


458 INDEX, 


PAGE 

eae Mechanical (Ores).. PUTER TEEPE 
of Base Bullion... 4.3% com ee ee eeesseceseccceccccessssces:ses id 

* “Copper ingots,..~.s\s ence erases ecasec sees t ee sis & sine pipiens mia 

He By COONCEMUE ALCS rs gions 5 Sone a'eta bit vba b08 6 be oe 60 0'y 0 Vmipleietne 3. 

£6 oO FUE CNStat Cr ans k ss ee Nous sobs ee ac ac ovehiehe oo 0 05/5 a bales #5 oan eee 

“s Seo CyOM UNIO sais sa se ee bale) ob ede ede e cee ees s hisb bivpeutnte tities 

why ‘* Pig-iron and Steel........ Fe ee a do. 09 0.6 bic-ow eioth se iaie a ae ean 

he SO Matlesmng cys mares = AE wipe - » evcbeueeeeu ees s 6a elon nmree 

Ze SSO STLVOLIERAUIION sate a € 5, 005.5's05 210 be ohio eels +0 be sen bie sath a erste misters 

tt fe Silver Sulphidés,; .'..0siciea oss cle wats susie teen 3 8 as sya ieee 

a $8 Slags.c veces tre snes oes cens cece sce s 6% 6 sae emis eieet nts 

a €¢ Tailings...s 00.0 snes bees bavnent ones ss eee ¢ oni brine ae 
Scorification..... da Bapben eee pale ah bis tree ale 4s cea ee ee Pe re hos - 125 


re Assay Gare) Table OLN este wer oleh © © es -ousle = iia eel ieee 
aE Assay for.Gold and Silver... 5.5.5. = =a sees RY eee 4 Pa 
nF » Loss of Gold ‘and Silver in. cn. < 6 reels cere oa ofo.p bets tet aie ee 393 


SCorinerss - wus «tas a0 ven eee ST ERTS Oe stb lb e's wie Bip ee 
Selenium in Refined Copper...... cb bees bese be oe vee 6 ctystelsip slennnenmen 414 
oa est for (Blow pipe). ssscus << 66 o's baa v oe 5 whem see beeen ME 

ae oes (Qualitativey. 3s es< Pa er a 8 wien ule alee a ae lovelaate ea ena 
milica (lags). wae pe ane sees Win eee eo oes ee is Acs ¢ 0 we sd'e bolas, wale wie ata 
i: 4p SGLELMIDALION OL Noe vten ene eres RE Aye one ee rhtae mete BPE Pe esis: 

«*> in Clays, Determination of... 7.5.16 Peas 0 06 Splerese biktemteieiear ar re es 

«< —** Copper Furnace Slags, Determination of............ pate cee ares 04 

sc. ** Iron: Furnace Slags; Determinationiol. >. s<eatass snes s 6 sic aw eleleigemenes 
*<+S* Tron Ores, Determination of: .2. <u. <chieers 0.0 0 ws 0 945 pele» eee 
Lead Ores, Determination of jo... aeec 2 016-0 00 89'e coh aaa secccess 79 

«¢ “Limestone, Determination of...... statwrereie vols timo RIES oe oe cee eete 84 
‘s* “Mattes, Determination Ofinc.us > ass 2s ae ssn eee s/s ensel eas hi eiy ete 

«* ‘* Natural Phosphates, Determination of... ° 00.0 sues eee ease SOE 

‘¢ =“ Silver and Gold Ores, Determination of..........0- oe ok sinlttele siete 

«| “* Slags (Lead), Determination of........ ¢njnlerere a ae eave aves ov thea k SOO 

“ «* Titaniferous Ores, Determination Of...........++. PCr aay 87 

wan, sl est for therPurity ofc. eee Gee MEWTEN Pi be 86 
Silicon in Jron and Steel; Determination Of 70-7. e es 2 0s 0.5 ba ps gitle esto game 
<* ** Commercial Aluminium, Determination of.............:.-+sss 290 

‘o>, bestdor( Blowpipe). vvaeieenss Speci ¢ 0a -64 2 0 say oes se pee 

BAR hee “*” (Qualitative) Aes re 5 6 a'0 Siu oo'ce ea inn 5 eieie ales eine eens 
Silver Bullion Assay....... shen siete uae le SAC oa eee en oo cue Bivle de ice clateesin ce mnenae 
rf eS SAM DULD Oban crencteta untae ares <eiehe ashes ee APNE E Re ko 
‘« Chloride in Ores, Determination of........ ee es eae 

‘**  Crucibles.. os vues no bee cece lem ibe ce 0/06 sie aie eih late tiketn alsin 
va NOrntinleeet noe aretial «i Ba tetotatces becccecvesovacescsesensstaess 120 
¥ ace OL TENS AS ahora: ee thets Seale o¥.0 0 00 a's et 5 ais Sr ate 122 
** in Base Bullion, Determination of.............0.. 6 0 é 00s 5 ate. ain ais eee 


INDEX. 459 


PAGE 
Silver in Copper Mattes, Determination Of.....cssccccssscccscccsecsceccs 250 


MUR CES MIICIELINUNAUION Of. sce cpcccseectcsccccecvocestecescesees 122 
“« ~“ Silags, Determination of...... iy ein Saintes disiep sia s sic Mialcstwicsaiciet se eml aC 
‘« , Loss in the Fire-assay for..... eile cement eisis' cissie ee is e vers ey er. 386 
S Nitrate (Precipitant).........0+ ahaa s Mavis Wel valaie.eaateles's «se sie eer a CaenT D 
RTOs eAMalsamation ASSAY Of..ccccccsccscccceccscssosesecccscee 201 
se «* , Chlorination Assay of........ Rute e Feiss a Ceo vines vatats viele re ead 
$f ** containing Metallic Scales, Assay Of,......ceseccscces Renton ioe 
*¢ , Determination of Alumina in.......... giwetle wees sieses sees LO4 
= < a ‘* Galctum in... .- site Snre e jeietstaeraieves cas crs ate e217, 
Re ‘ ne Wa Fda) et eee par sienicias' sic atae-a tie a's ielete @ aya . 178 
oe és: $3 MMV C ILC SITARILY stotalae' tauss/aic aries sipis eleb «sie +’ vee 223 
< a 4 Be NIAMS ANSE, 65. 5+0 » « Aaron og seeeeeee 198 
‘o nS a ECAR Grols cto 6 at aais ie'eyel ss preteens we sfe vets TO 
a Beer eCHANICA ASSAY Of. 6 oss. .e0 asc cusccctevss fe SEs. crsteve aia 417 
je scorincation Assay for........... OE COO OE Oe ree. Eee 
amet piiges, sampling Of... ..2.2cssecess Riv ulsieaa’a wae visemes ate ene ee 20 
oe REPENS SAVIO cen asleep sso Wise e cee ein pe sitvees ees wee suai she se ai0 252 
fe euipaides. Loss of Silver in the Assay of.........+.+; tt Sisarenee, <p 394 
eemeouonate in Ores, Determination Of.........s0s06s Hvine eevee, Cu seeeeeS 
=, © reparation of Pure........ rite MAGA SeeeEA Sistecate sath bea fycs Gslgagee s Oy 
‘«’, Vest for (Blowpipe)........ Beek S atare cicte area c Roiivareti ea ccc ane iets 34 
= jee (@Qualitative)....... Mesicter: stare sia. Reece ets Cornet tit Srectiteies Pe slate 45 
pave AMalysis Of ..;......0. Secarestals Sabine eres! wie le ote evi os ea: ¥ 0 Me ig: oe, 
I TOGO oie gy cis ow aie ss pai ds ese selec se eeeces lake nn Nea cra Tents os Le een 
Seeea Or oriening,Lable Of LYPe... 6.6. c.ce ee ssccsccsesnvesnes 338 
Smith’s (J. L.) Method for the Determination of Alkalies........seseese++ 230 
Peeps cCetate CE TeCipitant). 2.35625 - is. Diereteieits cata CRO mC vemas ce re 
wemeandelotassinm, Direct Determination Of, . 2.020050 cscvesecsesss 229 

J . « pelLtdirect:etermination Of, 4623.00 envececy oes . 228 
SemersiParnonate (P1UX). 02. os csc sc cae sc) eelesess aieishatetclere’s Saapreacpceic ey) 

Beem catporate (PIUX).. 52... sense. Sh SA On steccccccccsceese 66 

“ sf (Precipitant)...... pelos ste Cotaterterelst tata wisigia Gre are%h wyeie'e vin cies Mee 
SIP OEASe (EIU). we cute sence segvesss Uta wrest tekete ntale's ote ahi ates ese) 

z RCECIDIL ANE hows ase 'c.e vc reir a7 o oie 'sa ese «4,8 Rretele ths Sieacacigeeey a 
eariypostiohite: (Solvent)... ..-.00s00 sees ene AOR SASL EOONEL SOLE Ue: 

i Nitrate (Oxidizing Reagent)...... SWis e cusleie cacaletea a MCR E inaie vielen ete ys 

a * OPUS Yutricieals si3h 40°50 os Pais Wicststass cre sous sretes inte salsa e(eia.sie gee f 
feet onide (Precipitant)......6. .0.e. § Seater eis nif wa sic ale shag cicie Mee To 

«¢  Sulphite (Reducing Reagent).......... AB ib deee te ME wee chee sits ce utsele ETA 
icenerest tor (Blowpipe). 2)... ...-.- ehiatale dis aie sets c aielna ate. dats atsno stacey 

ee Se a OUALILALIVE) on. 5 5 on ecco 5 @ me eters as Medora Ce cceien ccncee nie cemeAtl 
memceniatcer inavater, Determination Of ....... ccs eececcscesscvcsesacsce 274 
Solvents.. BMT aia date Geek tse) Wao al a) ech jore e's ace cre Sele leieiauiets/s(ecs7ate n/a a's ale fe OG 
Specific eravity ~ fi Weight of Gases, Table of the............ ron £4" 


“s ee Determinations #680 6 8 9 ¢. 6.6.8 '@.6, 0° ¢ 8 2 eeeovesvevpe ete eevee eeeeeeee @ 293 


460 INDEX. 


PAGE 

Specific Gravity of Coal and Coke, Determination of........cessesssesess 200 
a - ‘* Liquids and Corresponding Degrees Beaumé......+.-+ 297 
DIL SAO VEle a vce wanes mes ence cone sesienss spasancen s0p ein asin miei salma samme 
Standard Acid Solutions...... Coes eeee cence ences s spee cesiess sieamaatl a nmnmenn 
Sh BEAK AS OMICIGIS sie 4's 5% nets inte teteeeats once ccccotesesceseestsens us 
Stannous Chloride (Reducing Reagent)....... 0 oe ec ccecocesccesisss cannes eae 
Steel, Determination of Combined Carbon in......cccccccccsccccccesecs L110 
oe sh * Chromium 1ne.. . 4/0200 o4csleunee tg 4a elses sens 
cs se AOA CTE NS) AUC OA 6 Soe 0 00 ose 00 0e 6s 005m 6.0 nnd a eines 
vh as $8 Drom itt, «sas 4 ic0c 0 opsiciee 090 ee netein etisalat 
As os ‘¢ Phosphorus in..... vec ccc ccc ccceescccscecesss 100 
“6 = SAONICOM AN gales wie elena MTePPTe ee oe ey 
es < ATRL ENING ine shen Cac cccescces eccccvecececerecs OA 
zs WY ** Total Carbon in... .«.s.00 s/s ws ov esasteiciais te eiatele senna 
Stoichiometry....... ive Aecerarte Meron sia lutein wid <ts s/ace ade ooo sop alae mete oe 321 
Strontium, Test for (Blowpipe)....... eaee Seve bes © os. eletenis ie Ghersheg sien en 
ay ss SS (Oualitanve). ams. cone bee c 0cm sen 6a wale a einieinie ei aie ss 
Sulphur, Determination ot. .seon cece bees WEETewi oe one 
oe in Refined Copper, Determination of.,..<5 «0s \sss.0ussieeeeta anne 
Sulphate of Silver in Ores, Determination of..... .. oss essa ae eeenie ene 
Sulphide of Ammonium (Solvent)............ cedet sees 06 bass eaierela eto 
Bs A J (Precipitantin.... TWITTER 


«  & Sodium (Reducing Reagent)...... «a's Se aie’ shel stare eis baie ae 74 
Sulphur by Absorption in Alkaline Solution of Cadme Sulphate, Deters 


Mination Of 6.026006 esc) wie wees snes mola ans yoo eee see 96: 
Sulphur by Absorption in Alkaline Solution of ene Nitrate, Determina- 

tion of..... Se ny a Meee. aly ae ose ceresensegs es on emesis mace 
Sulphur by Fahlberg-Iles Method, Decraipation Of... a essere ons siecle Sica ee tamne 

<<. 4*Fire-assay, Determinationiol\..:.5..4.5e vere ere - OI 
Sulphur by Oxidation with Potassium Chlorate and Nitric Acid, Determi- 

nation of...... WET AN SS Sivi'vie:& ary: wtealie a Cece ere eocccecesercccccececes QO 


Sulphur by Volumetric Method, Determination Of......e..ccsecesseceees Q2 
Sulphuretted Hydrogen (Reducing Reagent)... ... 0. «sss snisess sates Sa 


tf “A (Precipitant)......2+.0ccse sence eae eleeielsatients rmeneas 
Sulphuric Acid (Precipitant). .. <<. <2... secs-00s 05 0s viele 5 esis hietelenn ann 
os aie (Solvent)... --cecccoscsvccvccceccececcesunspnssiele seme mmcl 
ss ss in Water, Determination of... ... 2.0.06 sseelses eiscsls sae naya 
Sulphur, Test for (Blowpipe)....... oo nccccecccccecevcueeecsee nb asina seu mnae 
se 66 (Qualitative)... .cscccccccccccscceces sonssepesceessss AG 


T 


Table of Atomic Weights....0.accvecceccscceveceresoscnces nae se wena 354 
“© © Crucible Assay Charges...ccccrccccccescccvevesccccccesccccees 129 
oe *©Factors ... «.c.c0c 6.00 so od 0.0.@0 810 p08 .0 eee 6 fps eels e nie nieteteatnieie tant iennae 357 


INDEX. 461 


PAGE 
Table of Gramme and Pound HOUIVAICNIS Nic oes cate tease sec hees cad coos 257 
emeeercotiication Assay Charges. co. cca ness sresccccsccsecses 124 


‘« “* Specific Gravities and Weight at One Litre of Various Gases..... 356 
Table of the Specific Gravities Corresponding to Degrees Resumes of 
Liquids..... cece ceecerscones PMisis salssjs ers a We vS.eeises ¢ ns ets 69 vn wepis aie 207 
Table of the Tension of Aqueous Vapor......... Pap eisie.eris's vee pee vehi sie S55 
‘« « Type-lead Slags..... Soca ielsiacisisicleleinis a icirisaieih'e'sisie¢s\s'asiéie @e'vises ke S350 
Bee umetric DElerminations.......c.scesccesrassccerccecrserces 308 
MeeVee UtS ANd Measures... .. ccc c cde ccee ve Sites cam siete e eiatet sieiteste 353 
Table of Weights of Lead and Silver to be need in the esky of Silver 
Bullion..... one ae Rei Rer tale inte «wie avs epi sicie hols mateials Seen eee 238 
Table showing the Characteristic Properties of Various Metals........... 359 
on 4 ** Electrolytic Precipitation of Various Metals..... wonese 355 
ee uy Gemtstopertics.O1. Precipitates... 66s onecene cs ase ee sie eet 300 
ESPBVIGUACIC (IRCATEN),.. 6... cer es ecesvces SOR ROG Pee IOTROnE atest siete TO 
Tellurium in Refined Copper.......... ET SUGARIC Poreleversiety ste aide. « Sac sute cates a4 
SUT CStRLOTIULLOW PIPE). 4. atc ccucecisiccscvesssecesiesceseavce ns 30 


a Peete I UAlILACIVE) Sei. eek cee os os veevcccvccecesesccssses 40 
svension of Aqueous Vapor, Table showing the.......cse-sscrecssesescses 355 
SM ALE yen Zo Geis ciel lai diviaie ='s's,e Sis eis eos’ sinewe sce edhe ss 124 
PPGSES, DIOWDIDC. «ox 2 oe 2s cece cece cee's Reretetedlacstecfote's creisis's estes. sree sieia’e oe eine ee 

RP JUG IUALIVE. 2 an a ce e's wo ewe es een eressvcesecccceceseerosccscse 39 

«* used in the Cyanide ProcesS....cscccccecccccce socccecccecseses 401 
im, Fire-assay fOf....5 00.00 AP Gre Ae AOI COOOL ERY @ wig ate 
fu, Wetermination of... ....co0es Phas Ses @ ceslelcnee ese sisinesicssvcoee 15D 
Ste COW DIPE)..i5 5 ccc c cree ness csccctcoencesscceeteeseccsns 30 
Seems ee (A DIALICALIVE) 600s ss cee Coe siscwescceeesscyedccscvescossice 4D 
Titaniferous Ores, Determination of Chromium in........eeesscesesesees 189 
. ie Hy ‘*¢ Tron StF vadiee ce tinte cena eaves Mee LOS 

“ as of ** Silica Sete ew issavis ols orieisne oslo fal 
Titanium, Determination of..... Siigicls Ae vite eeisie ds ess bios © siénin'eivicls 0 esis ELOO 
SNE SLPLOL | SIOWDIPE).\.cs'cs oslecv ccs ccccecesecesetcrsetesvewsse 37 

4g Pee O(OUALILALIVE). crow cy cceccncesccceccsessveccesevesse 47 


See ear OO. DISTEPMINAtION Of ....s-cccccccccccccccosesecseevesenesees 100 
Tungsten, Test for (Blowpipe)...ceccvccccccscccccccccccccccccccccccsess 37 
Es “* ae (Otalitative) .is.occscccrccvovcescessesesecaseeseees 47 


U 


Uranium, Test for (Blowpipe)...cccccccccccccccccccccccccccceccocesccs 37 
es -y LY (Qualitative) ..ccccccccccvcccccccececcccccccscccecce 47 


V 


Vanadium, Test for (BIGWPINE) ciecccese sduc cee ep eee toes tenes ose sstie cc 38 
ce Ud ac (OUalitative) oo ccccnccipeas ccnaevecaspvesescsenceces 48 


462 INDEX. 


PAGE 
Vanhing Plague. .sistssetscocecccbdcchshssse isu dcase td su cana 422 
Vezin’S Jigss.cccsvens voce cenpoedcscsntevabssecth bes bs be snes 421 


Volatile Matter in Coal and Coke, Determination of..........seceesseeess 203 
Volhard’s Method for the Volumetric Determination of Manganese....... 198 
a A Py 6 el a sks **) Silver,.d ta sees eee 
Volumetric Assay of Silver Bullion, Calculation of the Results of the..... 244 
‘ Determination of Arsenic...:..5...0:0s css shan eeuiens sane 

es as ** Cadmium... .sss00s6s 600 46 ses nee See oe ett enn ee 

= . See AICAUY acre PeRrErrrrr nner yin oes 

“te ie ** Copper with Cyanide Solution.........e.02+ 154 

a as << **- by the Iodide Method 2... 6:5 sun poe 

wh we ‘** Lead with Molybdate Solution.........++2++ 142 

ce xe heey ‘< Permanganate Solution.........- 139 

ae “6 ‘* Manganese by Low’s Method......... ide 

=: be bh a ‘* Volhard’s Method........... 198 

“e oy es gs *¢ Williams’ Method.......0:+++ 197 

ste ud ** Phosphorus by Emmerton’s Method......... 100 

ee 4! 3 A ** Handy’s Method: ovsm ssc seats 

a6 as ** Silver by Gay-Lussac’s Method......... pak 60240 

ae ahd se “ “Volhard’s Method2eie2. eee 245 

ae ny Bt ‘© Sulphur onsen ann eaieet eee Dare CP es +s Dee 

Me 6 vn ‘« by Elliott’s Method. .vc.css 0 osism sy seen 

.s SE AING. «oases vaso bs eee ie One ss are eee 

da Determinations, Table of. .... 30.07... 0 oe ste ee AL ee 
Solutions, Calculations involved in the Preparation and Use of 328 

Von Schulz and Low’s Method for the Determination of Lead............ 139 
ds a. vi es “ eid es ss “6 Zint. ccc ce ees 


W 

Waller’s Method for the Writing of Chemical Equations........eseeees++ 314 
Water, Distilled LR cera ieetes ks ote ple le ied bile tn ae «bien Hime eee LSP 
s, Analysis ‘of s.% sic v's o's ae wna ais tease elena ene is: oialet ep a anameee 274 
S¢ |, Determination: Of:..:... 2 saves %-4) sine 5 nee p> 5 = ten en II9 
“¢ in Natural Phosphates, Determination of........ os = eh ble voip ewaeieeel cs 
Weighing ss:h2 sc carte ing ole careimneretieoiee oo 2 oes ne bo .ceie al wip leant aia tat nan 
‘¢ Gold and Silver Buttons..... Bfatetatsc oe cin eseced autaumnne obs 's ae eihes quem 
Weights... saat os ee o's 0 as 0.0 00.00 066 oss © oie eteis agi taly anna 
id oa Meseures’ Table ore peti eesiatolaate eaters oe 9.0 osin ls ee sib segs a 
“, Lableof Atomic wes e's ces cere ae a's: sapels seen AS $i > sivas anes 
Weller’s Colorimetric Method for the Determination of Titanium......... 190 

Whitehead’s Method for the Determination of Gold and Silver in Copper 
Matte. cess ogee aneas aim Slee pee’) 6h 07s led) 2s taker ee aes eo en ete. ose 250 
White-léad, Analysis of... 2. ..2-00565 00 060i 6 odes bicomi shen ett yane Canna 291 


Williams’ Method for the Determination of Manganese..............++++ 196 


INDEX. 463 


PAGE 
Wind SRD OMIT TCACE Tinie safle s loli cesses sc sie ceed Secboces ¢ee86 seb secbac 55 


Writing of Chemical Equations. ......scccccscveccscccccsctccetevessees 312 
PAM CE TECIPICATIE) oes oes cece cc ccccceseccsacsccscrccsccccccosccsosess 92 
‘¢ , Determination of....... SATvene sie sian eves sald wale sds gyelad'e's' ss 0 6se0 a ee ae » 20% 
«« in Ores containing Cadmium, Determination of.........eeseseesees 210 
Spee IA RS PRSLELMIINALION Of... 0... eve seve seve cess eseccscccascseecs 210 
, Test for (Blowpipe)......... Upiniete silt tev seins a0 Beies sisieoes vce toees bh Se 
66 FF (Qualitative)... ccccccccccccsccccccvcsescsevesccccocccess 48 











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Peabody’s Naval Architecture. . sa 6 0.06.58 afe dwie ¢.« 6:ke lea 6 6 giaieine ann nnnnCnenas 
2 


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* Phelps’s Practical Marine Surveying.........ccececescscceveecses s BVO, 


Powell’s Army Officer’s Examiner.............. LBRO VOI MOISE I2mo, 
Sharpe’s Art of Subsisting Armies in War..............c.0.. 18mo, morocco, 
~ Walke’erLectures'‘on Explosives: ..:)...6 0... ccccecccecccccecdece. 8vo, 
* Wheeler’s Siege Operations and Military Mining..................0.. 8vo, 
Winthrop’s Abridgment of Military Law.............cccccccccccecee I2mo, 
Woodhull’s Notes on Military Hygiene......... malalstareieherche srereictars nickeca 16mo, 
Young’s Simple Elements of Navigation.............eee0- --16mo morocco, 

Second Edition, Enlarged and Revised....... ceeeeeeee LOMO, Morocco, 

ASSAYING. 


Fletcher’s Practical Instructions in Quantitative Assaying with the Blowpipe. 
I2mo0, morocco, 


Furman’s Manual of Practical Assaying.............ccccccececcceees 8vo, 
Lodge’s Notes on Assaying and Metallurgical Laboratory Experiments. .. .8vo, 
ivers Manual of:Assaying ...ewdsndi oii oo. el. eae eee bl I2mo, 
O’Driscoll’s Notes on the Treatment of Gold Ores...... WAG. SLE 8vo, 
Ricketts and Miller’s Notes on Assaying..... sa stetey Rite Lee. SIR Sve} 
Ulke’s Modern Electrolytic Copper Refining...... tls Se lite Ae FELT 8vo, 
Wilson’s Cyanide Processes...............sece- Bidet cadence. es or ekallo, 
Chlorination Process............-.cececeees BG's ove Dvedion Tope SAMO, 
| ASTRONOMY. 
Comstock’s Field Astronomy for Engineers.......... Seeds osecs sc cs aeiDe 
MPEG Wr TET Ce ene wed c eas acess anesobe SS Ii FO 
Doolittle’s Treatise on Practical Astronomy........ Lamnmsiritaioc: eee ie 
Gore’s Elements of Geodesy................0. artic stare Bae bonnes e cine a eee 
Hayford’s Text-book of Geodetic Astronomy. ............ aseneee rer Torts 
Merriman’s Elements of Precise Surveying and Geodesy..............--SVO, 
* Michie and Harlow’s Practical Astronomy.............cceccccece ..-8V0, 
* White’s Elements of Theoretical and Descriptive Metonoriy. eeceveesLAilO, 
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Davenport’s Statistical Methods, with Special Reference to Biological Variation. 
16mo, morocco, 


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Westermaier’s Compendium of General Botany. (Schneider.).......... 8vo, 
CHEMISTRY. 
Adriance’s Laboratory Calculations and Specific Gravity Tables........12m0, 
Allen’s Tables for Iron Analysis..............cccccceces mete eee ee teas 8vo, 
Arnold’s Compendium of Chemistry. (Mandel.).................Small 8vo, 
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* Austen and Langworthy. The Occurrence of Aluminium in Vegetable 
Products, Animal Products, and Natural Waters.............. 8vo, 
Bernadou’s Smokeless Powder.—Nitro-cellulose, and Theory of the Cellulose 
IBC SM cracks e a\s cvs co. ste-n, 2.4.08 a1 Rieke cua ote ware trae ays isles kas 
Bolton’s Quantitative Analysis...... rg I te crmpite du ahiin tate ce «2... 8V0, 
* Browning’s Introduction to the Rarer Elements ...... cele teretors os «nen VO, 
Brush and Penfield’s Manual of Determinative neces icees SRT RGAE Beno Svo. 


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Cohn’s Indicators and Test-papers. sprees tenet erccecerececer ence oes 

Sr TEI aan 4 nin, «ns ain Xiniee Vigil tisha a oak ® OO 
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Effront’s Enzymes and their Applications. (Prescott.)........++20+++e0VO, 


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Erdmann’s Introduction to Chemical Preparations. (Dunlap.)........12mo0, 


Fletcher’s Practical Instructions in Quantitative Assaying with the Blowpipe 
12mo, morocco, 

Fowler’s Sewage Works Analyses...... + ness po eRe BO .-...12mM0, 
Fresenius’s Manual! of Qualitative Chemical Analysis. (Wells.)......... 8vo, 
Manualof Qualitative Chemical Analysis. Part I. Descriptive. (Wells.) 8vo, 
System Instruction in pexgaa a: Chemical Analysis. (Cohn.) 

4 VWOINS. Sci: cee Aes SETS ET RS oh: GE Pe ee ee ee Ta 
Fuertes’s Water and Public Health. Eye ee tay eae on ave sips aus whee Lala 
Furman’s Manual of Practical Assaying.............-+. fess 3e vba 
Getman’s Exercises in Physical Chemistry..........2.-+.seeees «2*oan 4 T2205 
Gill’s Gas and Fuel Analysis for Engineers..............-+- at dasiZ ...12mM0, 
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Lassar-Cohn’s Practical Urinary Analysis. (Lorenz.). ...........+-- I2mo, 
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Elements of Physical Chemistry.............ccccceecscecccees r2mo, 
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Voisls abies sf s2 cet oer es oo. 4 5.2 5 * asta ee Large 8vo, 

O’Brine’ s Laboratory Guide in Chemical Analysis..................... 8vo, 
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Poole’s Calorific Power of Fuels............. eee ceee rece veeceencs .. .8vo, 


Prescott and Winslow’s Elements of Water Bacterinlagss with Special Refer- 
ence to Sanitary Water Analysis..........-cccessecscecees se L2Mo, 


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* Reisig’s Guide to Piece-dyeing...... ccc ecw ccc ccc ccc cece A he eR 8vo, 25 © 
Richards and Woodman’s Air, Water, and Food from a Sanitary Standpoint.8vo, 2 0 
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Ricketts and Miller’s Notes on Assaying...........ccccecccecccecccecs 8vo, 3 00 
Rideal’s Sewage and the Bacterial Purification of Sewage...............8V0, 3 50 
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Quantitative Analysis. (Hall.).......ccccccccccccccccccccccccseSVOy 4 00 
Turneaure and Russell’s Public Water-supplies........ cdddddecesceaes sOV0s 5:00 
Van Deventer’s Physical Chemistry for Beginners. (Boltwood.).......12m0, I 50 
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MBEDUCU EM Rate cc. sirtae fcc rece Rietc ctetsie' se eisiejniadicnmaveieite AL esa CO 


CIVIL ENGINEERING. 


BRIDGES AND ROOFS. HYDRAULICS. MATERIALS OF ENGINEERING 


RAILWAY ENGINEERING. 


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** Burr’s Ancient and Modern Engineering and the Isthmian Canal (Postage, 
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Elliott’s Enginecring for Land Drainage......... cisteinwiblostetate wie ra ses ck amo; 
Practical Farm Drainage.......... RAUNT . oO Solis. TZN, 
Folwell’s Sewerage. (Designing and Maintenance.)...........2+ c0c0eeSVOy 
Freitag’s Architectural Engineering. 2d Edition Rewritten....... oe ee BVO 
French and Ives’s Stereotomy.... 2.0.0... 2. vi ccc cc cece cece ce cces .. -8V0, 
Goodhue’s Municipal Improvements............0...008. PAIS 20) FE ...I2mo, 
Goodrich’s Economic Disposal of Towns’ Refuse...........e.eeccecees 8vo, 
Gore’s Elements of Geodesy............---000- SERIF: WEY, 22 BEAR S60, 
Hayford’s Text-book of Geodetic Astronomy..................200000. 8vo, 
Hering’s Ready Reference Tables (Conversion Factors)....... 16mo, morocco, 


5 


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25 


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50 
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Howe’s Retaining Walls for Earth............c. ccc ccccccccccceces I2mo, 
Johnson's (J. B.) Theory and Practice 01 Surveying............. Small 8vo, 
Johnson’s (L. J.) Statics by Algebraic and Graphic Methods............ 8vo, 
Laplace’s Philosophical Essay on Probabilities. (Truscott and Emory.) 12mo, 
Mahan’s Treatise on Civil Engineering. (1873.) (Wood.)............8v0. 
® Descriptive Geometry ..............0..00ccceecce tees oe ML ONOP 
Merriman’s Elements of Precise Surveying and Geodesy............... .8vo, 
Elements of Sanitary Engineering. ................0. 3 eS . -8vo, 
Merriman ard Brooks’s Handbook for Surveyors.............16mo, morocco, 
Nugent’s Plane Surveying..... 2... a0 i s sallespeeg AL ae eee 8vo 
Ogden’s Sewer Design. ...... s-clsie lets Salewinsi ols S05. WN. UES eee I2mo, 
Patton’s Treatise on Civil Engineering..... cecescceeeess+- OVO half leather, 
Reed’s Topographical Drawing and Sketching........... 3 i POSS ator 
Rideal’s Sewage and the Bacterial Purification of Sewage................8V0, 
Siebert and Biggin’s Modern Stone-cutting and Masonry................8Vo, 
Smith’s Manua! of Topographical Drawing. (McMillan.)..... Praag ir 8vo, 


Sondericker’s Graphic Statics, with Applications to Trusses, Beams, and 
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NrewWoUTNWNNNHU YN NADH 


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Taylor and Thompson’s Treatise on Concrete,Plain and Reinforced. (In press.) 


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Wait’s Engineering and Architectural Jurisprudence.................. .8vo, 
Sheep, 
Law of Operations Preliminary to Construction in Engineering and Archi- 


tecture. . cece ccc esccccccccccccccsccccec cece ccc ce-eseeee s -OVOy 
Sheep, 
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Warren’s Stereotomy—Problems in Stone-cutting................e00. .8vo, 


Webb’s Problems in the Use and Adjustment of Engineering Instruments. 
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® Wheeler’s Elementary Course of Civil Engineering.................- .8vo, 
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BRIDGES AND ROOFS. 
Boller’s Practical Treatise on the Construction of Iron Highway Bridges. .8vo, 


s Thames River Bridge.......... 0.4, + -snagskeisice, ogee ceeg taste Aan ween 4to, paper, 
Burr’s Course on the Stresses in Bridges and Roof Trusses, Arched Ribs, and 
Suspension Bridges:............ sie bo aos Gia cleeiguea ae mater 8vo, 
Du Bois’s Mechanics of Engineering. Vol. II...:.............Small 4to, 
Foster’s Treatise on Wooden Trestle Bridges.............--- enbists a a ato: 
Fowler’s Coffer-dam Process for Piers...........00.c.scceccetecceee e8VO, 
Ordinary Foundations.) 2. 0007 2 So ee 8vo, 
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Bridge; Trugsesiz5.. Sc, L2G. LO Woes oo eee 
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Howe’s Treatise on Arches........... oe ee eee ee CeO OR Dee ee a me TOn 
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Johnson, Bryan, and Turneaure’s Theory and Practice in the Designing of 
Modern Framed Structures................ccccceeee Small gto, 
Merriman and Jacoby’s Text-book on Roofs and Bridges: 
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Part IIl.—Graphic Statics. ...... 0... ccc cece cc cc ccccece ote een etOO, 
Part II.—Bridge Design. 4th Edition, Rewritten. PRPLEERS SE . .8vo, 
Part IV.—Higher Structures.............cccccsccccces iPS 8vo, 
Morison’s Memphis Bridge.............. ccc cc cece ce cececcccccececs .4to, 
Waddell’s De Pontibus, a Pocket-book ie Bridge Engineers... .16mo, morocco, 
Specifications for Steel Bridges.............. oo ORT ag 


Wood’s Treatise on the Theory of the Ganétrnctios of Bridges and Roofs.8vo, 
Wright’s Designing of Draw-spans: 


Part I. —Plate-girder Draws............cccccsccccccecs sf aR: 8vo, 
Part II.—Riveted-truss and Pin-connected Long-span Draws....... 8vo, 
Two parts in one volume..... Pe Pere AAR ee +0 - BVO, 


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HYDRAULICS. 

Bazin’s Experiments upon the Contraction of the Liquid Vein Issuing from an 
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Flather’s Dynamometers, and the Measurement of Power............. I2mo, 
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Ganguillet and Kutter’s General Formula for the Uniform Flow of Water in 
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Hazen’s Filtration of Public Water-supply........c2ccccccescscecses -OVOy 
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® Michie’s Elements of Analytical Mechanics.................. cows gee 
Schuyler’s Reservoirs for Irrigation, Water-power, and Domestic Water- 
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_ ®® Thomas and Watt’s Improvement of Riyers. (Post., 44 c. additional), 4to, 
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Water-supply of the City of New York from 1658 to 1895.......... ..4to, 


Weisbach’s Hydraulics and Hydraulic Motors. (Du Bois.).............8V0, 
Wilson’s Manual of Irrigation Engineering...................-Small 8vo, 
Wolff’s Windmill as a Prime Mover..........ccccecsccncseccceesces sOVOy 
are wn cc ou sv cece octltlivle eSwele t% se pONGs 
Elements of Analytical Mechanics............. BA ree de aii «.0+-OVO, 
MATERIALS OF ENGINEERING. 
Baker’s Treatise on Masonry Construction.........cccecescsereees ...8vo, 
Roads and Pavements........ Fic By oes Ge a ee 8vo, 
Black’s United States Public Works. ..........2---e+eeeee+e0e0blong 4to, 
Bovey’s Strength of Materials and Theory of Structures...............-- 8vo, 
Burr’s Elasticity and Resistance of the Materials of Engineering. 6th Edi- 
TOT, ROWED. ons cacviccncncccnscenasectccesencessenes cs 8vo, 
Byrne’s Highway Construction...........-2+--eesseeeee aleintansey xt gai ce 8vo, 
Inspection of the Materials and Workmanship Employed in Sagrancton: 
16mo, 
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Du Bois’s Mechanics of Engineering. Vol. i. AC TU Et te Small gto, 
Johnson’s Materials of Construction.............-. Bees Bebe aT eeuavo, 
Fowler’s Ordinary Foundations. ............ ccs cccc cress reer srces 8vo, 
Beer BS CAS ATO... 5 oe oo aim eee eres ee Gre ee ee ee 8vo, 
Lanza’s Applied Mechanics............cccccccccccccccccccsccsceess -OWOs 
Martens’s Handbook on Testing Materials. (Henning.) 2vols.........8vo, 
Merrill’s Stones for Building and Decoration........... RISTO AS Ere 8vo, 
Merriman’s Text-book on the Mechanics of Materials................. 8vo, 
BOE MME DEOTIN IS. 0. ei Sood as nie 0:2 saline ety? orad S)E byolans «0s sles I2mo, 
Metcalf’s Steel. A Manual for Steel-users. .............2-ccceeness I2mo, 
Patton’s Practical Treatise on Foundations...............cccceeeeeees 8vo, 


Richey’s Handbook for Building Superintendents of Construction. (In press.) 
Rockwell’s Roads and Pavements in France. ......seeeceeeceeeveee eI 2M, 


4 


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Sabin’s Industrial and Artistic Technology of Paints and Varnish...... Svo, 

Smith’s. Materials of Machines. 2... 25 4... ec ne 5 oe wnle oe oa yy os maintains I2mo, 

Snow’s Principal Species of Wood... 2... 1.6... eee eee eee eee ete ees 8vo, 

Spalding’s Hydraulic Cement. ......... 66. 1s eee ree ee eters I2mo, 
Text-book on Roads and Pavements...........-+-------+-+-++-:- I2mo, 

Taylor and Thompson’s Treatise on Concrete, Plain and Reinforced. (/n 

press.) 

Thurston’s Materials of Engineering. 3 Parts...........--..-+++-0+s> 8vo, 
Part 1.—Non-metallic Materials of Engineering and Metallurgy..... 8vo, 
PartAl—trontand Steel. 2. . 6.25 62s seve wc peel» » oo ripe 8vo, 
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Constitwents. 4.4 .. vcce etels siete welebics a Se 8vo, 

Thurston’s Text-book of the Materials of Construction.............-.-- 8vo, 

Tillson’s Street Pavements and Paving Materials............-.---++-++- 8vo, 

Waddell’s De Pontibus. (A Pocket-book for Bridge Engineee: )..16mo, mor., 
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Wood’s (De V.) Treatise on the Resistance of Materials, ne an Appendix on 
the Preservation of Timber... .......-. ee ccc cece c reece erect eres 8vo, 

Wood’s (De V.) Elements of Analytical Mechanics... .......------+--+- 8vo, 

Wood’s (M. P.) Rustless Coatings: Corrosion and Electrolysis of Iron and 
Steel, . cs « cio c ooo naptueranne. che Ute Gys'm ar? Gach © 6 c)e mie Tate tect Alia ie eae 8vo, 

RAILWAY ENGINEERING. 

Andrews’s Handbook for Street Railway Engineers..... 3x5 inches, morocco, 

Berg’s Buildings and Structures of American Railroads... ..cssu-n-areuey eee Ato, 

Brooks’s Handbook of Street Railroad Location............ 16mo, morocco, 

Butts’s Civil Engineer’s Field-book............--.++-+-++-:- 16mo, morocco, 

Crandall’s Transition Curve. .......sscccccecscerssseseee 16mo, morocco, 
Railway and Other Earthwork Tables...........-..-+---++e-+--: 8vo, 

Dawson’s ‘‘Engineering” and Electric Traction Pocket-book. 16mo, morocco, 

Dredge’s History of the Pennsylvania Railroad: (1870): 202 2¢-2RS8 Paper, 

* Drinker’s Tunneline, Explusive Compounds, and Rock Drills, 4to, half mor., 

Fishertsy Sable of iCubic Yards. 22.02.50! oc). See oe eee ies Cardboard, 

Godwin’s Railroad Engineers’ Field-book and Explorers’ Guide... .16mo, mor., 

Howard’s Transition Curve Field-book................----- 16mo, morocco, 

Hudson’s Tables for Calculating the Cubic Contents of Excavations and Em- 

bankments. : Sci Seth St EL eee eee ate ee eee ete ee earn cena ae 8vo, 

Molitor and Beard’s Manual for Resident Engineers. ..............-- 16mo, 

Nagle’s Field Manual for Railroad Engineers.............-- 16mo, morocco, 

Philbrick’s Field Manual for Engineers........-......----- 16mo, morocco, 

Searles’s Field Engineering. ........---e eee es eter ree eeee: 16mo, morocco, 
Railroad Spiral «2s <as.5545 «> as sa e+e 6 oS ene = ne 16mo, morocco, 

Taylor’s Prismoidal Formule and Earthwork. ........-----++++-+++--- 8vo, 

* Trautwine’s Method ot Calculating the Cubic Contents of Excavations and 

Embankments by the Aid of Diagrams. .........-.....++++-- 8vo, 
The Field Practice of Laying Out Circular Curves for Railroads. 
I2mo, morocco, 
Cross-section Sheet. .... ee ee er Se Se Paper, 
Webb’s Railroad Construction. 2d Edition, Rewritten...... 16mo, morocco, 
Wellington’s Economic Theory of the Location of Railways...... Small 8vo, 
DRAWING. 

Barr’s Kinematics of Machinery. ......--6 22-22 eseeeeee cece sere ceees 8vo, 

* Bartlett’s Mechanical Drawing... 2.5.0... 2+ ++ 022202 ees eee sees? 8vo, 

> ‘so Abridged Ed. ...~.......- «=9sepeeeeee ne eee 8vo, 

Coolidge’s Manual of Drawing. RTE E 8 eS ee paper, 

Coolidge and Freeman’s Elements of General Drafting for Mechanical Engi- 

TICOLS de. sc duchduesShcnese ads %onw wicnrubbencickenSwcuenccek? Scipiae canes Naima Oblong 4to. 

Durley’s Kinematics of Machines. .........-- +++ essere eteceerr rece 8vo, 


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Hill’s Text-book on Shades and Shadows, and Perspective.............. 8vo, 


Jamison’s Elements of Mechanical Drawing...............+...-- nie tha tite Svo, 
Jones’s Machine Design: 
Part)l=—Kinematicsvof Machinery: 0. 650. 002 ee. Se 8vo, 
Part II.—Form, Strength, and Proportions of Parts............... 8vo, 
MacCord’s Elements of Descriptive Geometry. ... ...------ eee ee eens 8vo, 
Kinematics; or, Practical Mechanism. ..........--- eee ee ee eens SVO0; 
Werte MITA WALZ. oye cn no op vhlv es ed lellwletldels ov odineutee se ob eae 4to, 
Welocity, Diagrams, .... . 2. 2... eee FG ee He lant ne le ne Sele 8vo, 
Mahan’s Descriptive Geometry and Stone-cutting............--.+++-- 8vo, 
Industrial Drawing. (Thompson.)........--- see eee ee ee eee ees 8v0, 
Moyer’s Descriptive Geometry. (Jn press.) 
Reed’s Topographical Drawing and Sketching. ... .......--+-se+-eeee: Ato, 
Reid’s Course in Mechanical Drawing. ...........---- eee eee ee eee 8vo, 
Text-book of Mechanical Drawing and Elementary Machine Design. .8vo, 
Robinson’s Principles of Mechanism... ........- +--+ e+e eee ee eee rereee 8vo, 
Schwamb and Merrill’s Elements of Mechanism..........-.---+++-+-+--- 8vo, 
Smith’s Manual of Topographical Drawing. (McMillan.).............. 8vo, 
Warren’s Elements of Plane and Solid Free-hand Geometrical Drawing. .12mo, 
Drafting Instruments and Operations. ........---- +--+ essere ees I2mo, 
Manual of Elementary Projection Drawing...............+----- I2mo, 
Manual of Elementary Problems in the Linear Perspective of Form and 
ACO e eos © 5 < 6 acre ss NA ed RTA aia te I2mo, 
Plane Problems in Blementary Geometry. ... ....--+-- eee eeees 12mo, 
Tar Fi BOTIELE oars 68h Seewne eargeyun F< gcomes PH tment nT tytn itunhates I2mo, 
Elements of Descriptive Geometry, Shadows, and Perspective...... 8vo, 
General Problems of Shades and Shadows........----+++eeeeeeee- 8vo 
Elements of Machine Construction and Drawing...........---+--- 8vo, 
Problems, Theorems, and Examples in Descriptive Geometry....... 8vo, 
Weisbach’s Kinematics and the Power of Transmission. (Hermann and 
RETA Oe ee Be OG Pact eily pixie ya's 8 > cpyetin a anh Shue es snes h 8vo, 
Whelpley’s Practical Instruction in the Art of Letter Engraving....... I2mo, 
Wilson’s (H. M.) Topographic Surveying.....--- +. ++ eres reerereescees 8vo, 
Wilson’s (V. T.) Free-hand Perspective. ......++.-+++ Ben ata alle ite So tatoge 8vo, 
Wilson’s (V. T.) Free-hand Lettering. ........ see ee eee ee eter reece: 8vo, 
Woolf’s Elementary Course in Descriptive Geometry 2. seca <5 t¢ = Large 8vo, 
ELECTRICITY AND PHYSICS. 
Anthony and Brackett’s Text-book of Physics. (Magie.)........ Small 8vo, 
Anthony’s Lecture-notes on the Theory of Electrical Measurements. ...12mo, 
Benjamin’s History of Blectricitystrscels «= 45 <osy o werisineioe seco ene lees 8vo, 
CRE LI as 2 cla aie eine staty sR T EES (“TNS 8vo, 
Classen’s Quantitative Chemical Analysis by Electrolysis. (Boltwood.). .8vo, 
Crehore and Squier’s Polarizing Photo.chnono graph... See Rash 8vo, 


Dawson’s “Engineering”? and Electric T raction Pocket-book. .16mo, morocco, 
Dolezalek’s Theory of the Lead Accumulator (Storage Battery). (Von 


SUM TURN, Peels As ea ans ity Meee AO Eee I2mo, 
Duhem’s Thermodynamics and Chemistry. (Burgess.)....:..---++++--- 8vo, 
Flather’s Dynamometers, and the Measurement of Power.........--- I2mo, 
Gilbert’s De Magnete. (Mottelay.)....... enn Sees Oe Ea 8vo, 
Hanchett’s Alternating Currents Explained. ........-----+-+--sers00> 12mo, 
Hering’s Ready Reference Tables (Conversion Factors)...... 16mo, morocco, 
Holman’s Precision of Measurements... ..-.------- esse errr rrr 8vo, 

Telescopic "Mirror-scale Method, Adjustments, and Tests... - .Large 8vo, 
Landauer’s Spectrum Analysis. (Tingle. Jiave Go le solo ar uche noes ester etary wacker aue 8vo, 


Le Chatelier’s High-temperature Measurements. (Boudouard—Brgess. )12mo 
Ldb’s Electrolysis and Electrosynthesis of Organic Compounds. (Lorenz.) 12mo, 


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© Lyons’s Treatise on Electromagnetic Phenomena. Vols.I. and II. 8vo, each, 
* Michie. Elements of Wave Motion Relating to Sound and Light.......8vo, 
Niaudet’s Elementary Treatise on Electric Batteries. (Fishnack.)...... 12mo, 
* Rosenberg’s Electrical Engineering. (Haldane Gee—Kinzbrunner.)....8vo, 
Ryan, Norris, and Hoxie’s Electrical Machinery. Vol. L..,............8V0, 
Thurston’s Stationary Steam-engines........cccccccccccccccscccses -OVOs 
* Tillman’s Elementary Lessons in Heat.......... OM fates teen 8vo, 
Tory and Pitcher’s Manual of Laboratory Physics..............omall 8vo, 
_Ulke’s Modern Electrolytic Copper Refining .,.........+eeeeee2-+++ 80, 


® Davis’s Elements of Law....... eovereseeeees 6G 018d o.92 a wisiee eee 


* Treatise on the Military Law ot United States... «<esse2) aueee ee 
bg Sheep, 


Manual for Courts-martial..... SSE RRO S eretere weceees- LOMO, Morocco, 


Law of Operations Preliminary to Construction in Engineering and Archi- 


tecture se. ee ase Cae cc ec Sees e's ese S's ce 6 ui eu Siew ote net 8vo, 
Sheep, 


Law of Contracts eeoee cn <u'e au neokeea Seale Mote Sle cee se emteunee ene anne 
Winthrop’s Abridgment of Military Law....... & via%el sia ale WES ete kis BE SHEDS 


MANUFACTURES. 


Bernadou’s Smokeijess Powder—Nitro-cellulose and Theory of the Cellulose 
Molectile 5. ccic s cc.c cre erevsivic.c 0 6 sc = cca eo sle\aceisip gierais etersatemeui ters 
Bolland’s Iron Founder...............00.4- a os 0.0 b:00.0/0 4 6 c/eipiers einrraane SERS 
*¢ The Iron Founder,” Supplement....... mst teeceeccees ne ee bale 
- Encyclopedia of Founding and Dictionary of f Foundry Terms Used in the 
Practice of Moulding ©... <\c.sic +c o:s'sieisiecs a1s}e's'alete/ersiele steiatars Ree & ponles 
Eissler’s Modern High Explosives. ..... ccc cccc cece cece ccccsccecees -OVOy 
Effront’s Enzymes and their Applications. (Prescott.). ...0-ccescncsngs Oe 
Fitzgerald’s Boston Machinist. JS Mine chester Sosie ¥ cé'e's #el¢ 0.6.5 Sealers sguate any ae 
Ford’s Boiler Making for Boiltt Maket§::.:-....++scssccceeccseess38moy 
Hopkins’s Oil-chemists’ Handbook. 1.2... tte c cc cc ccc ccc cence eves o -OVOy 
Keep's: Cast {£00...- cic sos accis 90046 -0u POPES PE sc ...8V0, 
Leach’s The Inspection and Analysis of Food with Soecigh Reference to State 
Control. (In preparation.) 


Matthews’s: The Textile Fibresso ev. o SES. oa Pee ie be tees Oot ee meee 8vo, 
Metcalf’s Steel. A Manual for Steel-users.............ccccccccccess 12mo, 
Metcalfe’s Cost of Manufactures—And the Administration of Workshops, 
Public and Private......... als S sleet a4 ee se OS ote Sb oe bee Ee 8vo, 
Meyer’s Modern Locomotive Construction......... eth Baa a ert ace 4to, 
Morse’s Calculations used in Cane-sugar Factories. .........16mo0, morocco, 
* Reisig’s Guide to Piece-dyeing........... cc cc ceeeccscccsons reise s 8vo, 
Sabin’s Industrial and Artistic Fechiioley of Paints and Varnish ...... 8vo, 
Smith’s Press-working of Metals... ....cccccccccccccccedccccsccsecce 8vo, 


Spalding’s Hydraulic Cement... 0.2... scccereccescsccecsacnscle geuce aig, 
Spencer’s Handbook for Chemists of Beet-sugar Houses. ....16mo, morocco, 
Handbook for Sugar Manufacturers and their Chemists...16mo morocco, 


Taylor and Thommen? Treatise on Concrete, Plain and Reinforced. (In 
press. 


Thurston’s Manual of Steam-boilers, their Designs, Construction and Opera- 
HLON stole cis wo urts Siwls, ateiele, orrerare BS Doe SUS Tales Selene ie eo was 

* Walke’s Lectures on Explosives... .cccccsccccccscsccvacsscesesas -OVO, 
West’s American Foundry Practice.....c.cceccccccccssceccscsceessI2M0, 
Moulder’s. Text-book . oi ca cvccevslescccsrcevcsdee povww outs eels DaIOy 


10 


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Wolff’s Windmill as a Prime Mover..... YF, FOTOS OOOO, 88 STS 8vo, 


Woodbury’s Fire Protection of Mills............-2--- eee cece eee eees 8vo, 
Wood's Rustless Coatings: Corrosion and Electrolysis of Iron and Steel. . .8vo, 
MATHEMATICS. 

Baker’s Elliptic Functions......0.cceeccccccccnccceccescccesersscns 8vo, 
® Bass’s Elements of Differential Calculus....... ie ccatenererehs (elale Sis.0 «oye e.8 I2mo, 
Briggs’s Eiements of Plane Analytic Geometry.....-.+-+++seeee++++-I2M0, 
Compton’s Manval of Logarithmic ComputationS.........++++++++--- 12mo, 
Davis’s Introduction to the Logic of Algebra... ....ceecesececcecceeees 8vo, 
® Dickson’s College Algebra............-- BAAS SOT Io Sb ne Large 12mo, 
* Answers to Dickson’s College Algebra. .....cceceeeeeccerss 8vo, paper, 
* Introduction to the Theory of Algebraic Equations .......Large 12mo, 
Halsted’s Elements of Geometry......csccccereeccecccrsccveccerceces 8vo, 

Elementary Synthetic Geometry. ....-..-+eeereccsecesceerececes 8vo, 

Rational Geometry. ..........eee-e0% ae oleae a TR eee I2mo, 


* Johnson’s (J. B.) Three-place Logarithmic Tables: Vest-pocket size. . paper, 
100 copies for 

* Mounted on heavy cardboard, 8 X 10 inches, 
10 copies for 

Johnson’s (W. W.) Elementary Treatise on Differential Calculus. . .Small 8vo, 
Johnson’s (W. W.) Elementary Treatise on the Integral Calculus. .Small 8vo, 
Johnson’s (W. W.) Curve Tracing in Cartesian Co-ordinates.......... I2mo, 
Johnson’s (W. W.) Treatise on Ordinary and Partial Differential Equations. 
Small 8vo, 

Johnson’s (W. W.) Theory of Errors and the Method of Least Squares. .12mo, 
* Johnson’s (W. W.) Theoretical Mechanics. ........+++++seeeeeeees I2mo, 
Laplace’s Philosophical Essay on Probabilities. (Truscott and Emory.) 12mo, 
* Ludlow and Bass. Elements of Trigonometry and Logarithmic and Other 


MLA DIES . Weicleccfelie bis 61318 SAAR aa: are a's exes 45% o oe 8vo, 
Trigonometry and Tables published separately.........-+----- Each, 

* Ludlow’s Logarithmic and Trigonometric Tables .........+-seeeeeee- 8vo, 
Maurer’s Technical Mechanics............--- SOO SIGE DehOd pale 8vo, 
Merriman and Woodward’s Higher Mathematics .........+-ese+s-e+e-- 8vo, 
Merriman’s Method of Least Squares. ........-- es eseccceecesereccees 8vo, 


Rice and Johnson’s Elementary Treatise on the Differential Calculus .Sm., 8vo, 
Differential and Integral Calculus. 2 vols. in one......... .omall 8vo, 
Wood’s Elements of Co-ordinate Geometry....... 5 bets SOS OIC Cio eS 8vo, 
Trigonometry: Analytical, Plane, and Spherical...........--+++--I2M0, 


MECHANICAL ENGINEERING. 
MATERIALS OF ENGINEERING, STEAM-ENGINES AND BOILERS. 


Bacon’s Forge Practice..... eR eer tne MEK Nocers Cees esse es ces ee silG, 
Baldwin’s Steam Heating for Buildings. ........esseeccer cress erees I2mo, 

Barr’s Kinematics of Machinery.........ccccccssseceees ete ces LOvU 
. ® Bartlett’s Mechanical Drawing... ........-esseeee> We MN eee er 8vo, 
ad - * hd Mbridved Hdss. co.cc sce e cet eet wees 8vo, 
Benjamin’s Wrinkles and Recipes........ EES FORA ENN enters coe ee ais I2mo, 
Carpenter’s Experimental Engineering............-.+-eeeeerereeees: 8vo, 
Heating and Ventilating Buildings...........-.--++eeeeeeeeerees 8vo, 

Cary’s Smoke Suppression in Plants using Bituminous Coal. (Jn prep- 
aration.) 

Clerk’s Gas and Oil Engine.............-- oh ati setoeM ott. Bi Small 8vo, 
Coolidge’s Manual of Drawing..........--.2-eeeeecerereeess 8vo, paper, 
Coolidge and Freeman’s Elements of General Drafting for Mechanical En- 
CT) «ne ee Oblong 4to, 


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Cromwell’s Treatise on Toothed Gearing.........-----seeeee erences 12mo 
Treatise on Belts and Pulleys.......cccccescrcsccccereees J. <fSlamoys 

Durley’s Kinematics of Machines. ..........-+++-+-++-e0% 32 et atlale See 8vo, 

Flather’s Dynamometers and the Measurement of Power....... ayes ce 12mo, 
Rope Driving...........2-0+eeeee> ehtlek A Oa dé eswealesieteinO, 

Gill’s Gas and Fuel Analysis for Engineers....... ee ..-I2mo, 

Hall’s Car Lubrication... ...... 0. cee eee eee cee eee ere r cree en eeees I2mo, 

Hering’s Ready Reference Tables (Conversion Factors)...... 16mo, morocco, 

Hutton’s The Gas Engine........ SST 8 wee ocsce Cano rags corre eee 8vo, 

Jamison’s Mechanical Drawing. ..........--- ee eeere reece ere reesceee 8vo, 

Jones’s Machine Design: 

Part I.—Kinematics of Machinery.............- eats ante aeetos 
Part II.—Form, Strength, and Proportions of Parts............-.--- 8vo, 

Kent’s Mechanical Engineer’s Pocket-book. ........---++-+e: 16mo, morocco, 

Kerr’s Power and Power Transmission. ........-.2.+-++-+e- avejeele na slecaene Svo, 

Leonard’s Machine Shops, Tools, and Methods. (In press.) 

MacCord’s Kinematics; or, Practical Mechanism....... «cists ss og. > aus ge 
Mechanical Drawing.......ccceececesereces ob ss 6 oe Wie aire wine Stet Oy 
Velocity Diagrams. .............--+- eceseneiauttets eS CSO Oo 8vo, 

Mahan’s Industrial Drawing. (Thompson.)........scsecssscececcces .8V0, 

Poole’s Calorific Power of Fuels..........-.cceccercccceccs ey re 

Reid’s Course in Mechanical Drawing.........-..--e2ec0: dd tha eee 8vo, 
Text-book of Mechanical Drawing and Elementary Machine Design. . 8vo, 

Richards’s Compressed Air.......... Be eis lere tate ena erator Sel tkaunts 12mo, 

Robinson’s Principles of Mechanism. ..........-.--- oun 0:0) aialnetee ogee 

Schwamb and Merrill’s Elements of Mechanfsm..............+-+++-+++-- 8vo, 

Smith’s Press-working of Metals..........----s+-+-e- mca tral tacten aah aia 8vo, 

Thurston’s Treatise on Friction and Lost Work in Machinery and Mill 

Work....... snob isis costo e 1d iiaiwi ocssavac cinke Giid nelebon: Cerne ia aa ae 8vo, 
Animal as a Machine and Prime Motor, and the Laws of Energetics.12mo, 
Warren’s Elements of Machine Construction and Drawing.............. 890, 
Weisbach’s Kinematics and the Power of Trarsmission. Herrmann— 
Kileis.): ase seen snes cee 5 0088 ore 2 abe enn 8vo, 
Machinery of Traviemiseion and Governors. (Herrmann—Klein. ). .8vo 
Hydraulics and Hydraulic Motors. (Du BOIS, cs sieaatey a ae aie 0-94 Qe OR 
Wolff’s Windmill as a Prime Mover..........-cccecccccccecesercces sOV0y 
Wood’s Turbines..... ein > alneh Wain Rae ee Conse ee Series: trate <lseeeeintimitia, tienen 
MATERIALS OF ENGINEERING. 
Bovey’s Strength of Materials and Theory of Structures......... Mb cagitatis 1. 
Burr’s Elasticity and Resistance of the Materials of Engineering. 6th Edition 
Rieseticet: Seba ter ar ac eatrnc site oeecetens aiisheinle ss. ievfoRerseaeats ees eeVOy 

Church’s Mechanics of Engineering ......0.cccsccecerseesscescvess 8v0, 

Johnson’s Materials of Construction............-eseeeeeeeeee Large 8vo, 

Keep’s Cast Iron imo Sibsipeeys uy atS oases ere ise ale See daitee seers 

Lanza’s Applied Mechanics.............++e-+es> aut, Ste scout bape la ase 


Martens’s Handbook on Testing Materials. (Henning.)..............-8V0, 
Merriman’s Text-book on the Mechanics of Materials................+-8V0, 


Strength of Materials..........-.e+eeeceees asp sinsett deamuraeae ...12m0, 
Metcalf’s Steel. A Manual for Steel-users...........0.2-012eeeeseee r12mo0 
Sabin’s Industrial and Artistic Technology of Paints and Varnish...... 8vo, 
Smith’s Materials of Machines. ........ccccecccceresvcresecsceeees 12mo, 
Thurston’s Materials of Engineering............--+.s+++0++--3 VOIS., SVO, 

Part/#Il—ITron and, Steel.....2.0...0<cceceserevesncsie sere sesetotasshesete nel anaieaees wee. -8V0, 

Part II].—A Treatise on Brasses, Brasteesi and Other Alloys antl their 

Constituents. Syosset wel CRESS SHS ee 8vo 


Text-book of the Materials of Construction.. eoeeeceoseereoeeeroverte -8V0, 
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Wood’s (De V.) Treatise on the Resistance of Materials and an Appendix on 


Che. PresenvariOniOl Liber, « . .ealteeedebebagbweds)~ sro aremeverous o otemnlett 8vo, 2 

Wood’s (De V.) Elements of Analytical Mechanics.................4.. 8vo, 3 
Wood’s (M, P,) Rustless Coatings: Corrosion and Electrolysis of Iron and Steel. 

8vo, 4 


STEAM-ENGINES AND BOILERS. 


Carnot’s Reflections on the Motive Power of Heet. (Thurston.)....... 12mo, I 50 
Dawson’s “Engineering” and Electric Traction Pocket-book..16mo, mor., 5 00 
Ford’s Boiler Making for Boiler Makers......... Jae Se a eves 18mo, 1 00 
Goss’s Locomotive Sperks...........-seeeeees Hes) ee <BeN Rte? 8vo, 2 00 
Hemenway’s Indicator Practice and Steam-engine Economy...:...... I2mo, 2 00 
Hutton’s Mechanical Engineering of Power Plants......... eeite Yo -enes 8vo, 5 00 
Heat and Heat-engines........ Ee! ey eae ian a Se ee 8vo, 5 co 
Kent’s Steam-boiler Economy.............. Hebe BID See. ta eoldacmnlk 8vo, 4 00 
Kneass’s Practice and Theory of the Injector..............+00- cheer 8vo, I 50 
MacCord’s Slide-valves......... Se INR ore. SS 5 BM ole i cles ee vCOVOg 2,00 
Meyer’s Modern Locomotive Construction...........+++0-- wocometeieet. 4to,3210.00 
Peabody’s Manual of the Steam-engine Indicator............... stag BANID og pPuSO 
Tables of the Properties of Saturated Steam and Other Vapors. -«-.-8V0, I 00 
Thermodynamics of the Steam-engine and Other Heat-engines..... 8vo, 5 00 
Valve-gears for Steam-engines........ Bast. bectsewomt {.9 Cae 8vo, 2 50 
Peabody and Miller’s Steam-boilers ..........--2+-00- tae 4. Sods. 8vo, 4 00 
Pray’s Twenty Years with the Indicator...... oSeDT Ss EMER RA : Large 8vo, 2 50 
Pupln’s Thermodynamics of Reversible Cycles in Gases and Saturated Vapors. 

SPR REE) he 0. Gm Sree seeFd «iss - ales sie 29 eae 12mo, I 25 
Reagan’s Locomotives: Simple, Compound, and Electric...... Si iron arate I2mo, 2 50 
Rontgen’s Principles of Thermodynamics. (Du Bois.).............--- 8vo, 5 00 
Sinclair’s Locomotive Engine Running and Management..............12M0, 2 00 
Smart’s Handbook of Engineering Laboratory Practice...............I2M0, 2 50 
Snow’s Steam-boiler Practice........-ccccccccccecsrcerscrenesccens 8vo, 3 00 
Spangler’s Valve-gears.......2eeserecececcccsscerccecceceerereces OVO, 2 50 

Notes on Thermodynamics... .....secccocccccccccccccececeeesI2M0, I 00 
Spangler, Greene, and Marshall’s Elements of Steam-engineering........ 8vo, 3 00 
Thurston’s Handy Tables....... POE Pie eM id a nce nieve apbiaiccerl vecyese/stekomneieis & 8vo, I 50 

Manual of the Steam-engine.........-.seeccecccseee eee 2 VOMS,, BVO, 10 00 

Part I.—History, Structuce, and Theory..........2.22eeeeeeee++-8V0, 6 00 

Part Il.—Design, Construction, and Operation...........-..+-++-: 8vo, 6 oo 

Handbook of Engine and Boiler Trials, and the Use of the Indicator and 

the Prony Brake......... Ki deGhielstsiersicia’s.c1 stile. Stacie atsiaiaieiel arses 8vo, 5 00 

Stationary Steam-engines.........-s-eee0- Sstctersie wininierelelsraieazin‘ole, © 8vo, 2 50 

Steam-boiler Explosions in Theory and in Practice.............. I2mo, I 50 

Manual of Steam-boilers , Their Designs, Construction, and Operation.8vo, 5 00 
Weisbach’s Heat, Steam, and Steam-engines. (Du Bois.).......... ..-8V0, 5 00 
Whitham’s Steam-engine IAGO aa a «can ue ere nie eT s noes ae ON OF. OO 
Wilson’s Treatise on Steam-boilers. (Flather.)............. HOB Seat 16mo, 2 50 
Wood’s Thermodynamics Heat Motors, and Refrigerating Machines... .8vo, 4 00 

MECHANICS AND MACHINERY. 
Barr’s Kinematics of Machinery...........-. se eeecceeeeeces cy buen soves 2° 50 
Bovey’s Strength of Materials and Theory Of Structyleseicwk elpre civ weinoinis 8vo, 7 50 
Chase’s The Art of Dattern-making, +... esac ceaseh ticmeiigsieaiet ley one L2i0y. 2 50 
Chordal.—Extracts from Letters..... Chot dsindupaees wanes vs siete eta aney ~ 2: OO 
Church’s Mechanics of Engineering. .....'.-seececececcecececcces es sOVO, 6 00 


13 


Church’s Notes and Examples in Mechanics.........0secseeceecceess SO, 
Compton’s First Lessons in Metal-working...........seesseeeeee---I2M0, 
Compton and De Groodt’s The Speed Lathe.............+++0.++2++--I2M0, 


Cromwell’s Treatise on Toothed Gearing................ Ae I, 
Treatise on Belts and Pulleys............cccccccccecvccces - ++ I2MO, 
Dana’s Text-book of Elementary Mecharics for the Use of Colleges and 
Schools ottacere se cnc co iciecoe we vic, wyepeuenhnlaa ie wee ole okela eretavenene «sae T2™MO, 
Dingey’s Machinery Pattern Making...........----+-eseeeeeeeeees 12mo, 
Dredge’s Record of the Transportation Exhibits Building of the World’s 
Columbian Exposition of 1893...... weeeeeee---4tO half morocco, 
Du Bois’s Elementary Principles of Mechanics: 
Vol. I.—Kinematics..... + ivlatuiersiee 0c S2SU SRS thie yet ee ee eee 
Vol? PIL, Statics nics. s oo se'siewie'Siw wale ain »/civ Ueiele date Sate 
Vol. I].—Kinetics.......... .... ewe e be eee nae} eee 8vo, 
Mechanics of Engineering. Vol. I.............-+-++-.-.--omall 4to, 
Vol, U..:.c.0 » © 5 hiv cnoisisilsae eae ee 
Durley’s Kinematics of Machines. ............cecccccccececeeecese+ -BVOy 
Fitzgerald’s Boston Machinist............. wt add: wee Co 


Flather’s Dynamometers, and the Measurement of Power............-12M0, 

Rope Driving.........ccccccccc ccc cscceccncccevecescccccce sk zit, 
Goss’s Locomotive Sparks. .....ccccccccccccccccccccacscccccccsces sOV0y 
Hall’s Car Lubrication... 1... ccc ccc cw cc cc cc ccc ccc c ccc ccctecsecees 12M, 


Holly’s Art of Saw Filing..............62.- S oaidieté 2 Siete Oh aha IID 
* Johnson’s (W. W.) Theoretical Mechanics » «oe tee eee ee I2mo, 
Johnson’s (L. J.) Statics by Graphic and Algebraic Methods............ 8vo, 


Jones’s Machine Design: 
Part I.—Kinematics of Machinery............-sccsescsesecees -OVOy 
Part Il.—Form, Strength, and Proportions of Parts...........+..-8V0, 
Kerr’s Power and Power Transmission............ceceescsccecceces BVO, 
Lanza’s Applied Mechanics. ..............cccccccccscsceces ste. 2e.. Bo, 
Leonards Machine Shops, Tools, and Methods. (Jn press.) 
MacCord’s Kinematics; or, Practical Mechanism....,.............+-.8VO, 


Velocity Diagrams......... WETTTTETET Tere te 
Maurer’s Technical Mechanics, ........cccccccccsccccsescescccesces OVO, 
Merriman’s Text-book on the Mechanics of Materials..................8¥0, 
* Michie’s Elements of Analytical Mechanics........... fe 0 SER BUST TCS 
Reagan’s Locomotives: Simple, Compound, and Electric..............2M0, 
Reid’s Course in Mechanical Drawing.............2ccsccceccccecees 8vo, 

Text-book of Mechanical Drawing and Elementary Machine Design. .8vo, 
Richards’s Compressed Air...........cccccecccceee SSE O IETS ose EB2NIO§ 
Robinson’s Principles of Mechanism..............-+e0- J velele® SO. 
Ryan, Norris, and Hoxie’s Electrical Machinery. Vol. Lo. esk cca eee 8vo, 
Schwamb and Merrill’s Elements of Mechanism....................... 8vo, 
Sinclair’s Locomotive-engine Running and Management.......... --..22M0, 
Smith’s Press-working of Metals.....cccccccccceccees EE irs 


Materials of MachineéS....cccccsccccccccsssacecemcrcnce noes tem DaiiOy 
Spangler, Greene, and Marshall’s Elements of Steam-engineering.......8vo, 
Thurston’ oF T brea es on Friction and Lost Work in Machinery and Mill 


erie te cen pl el SUI. WR. Ree 

Animalas a Machine dnd Prime Motor, and the Laws of Energetics.12mo, 
Warren’s Elements of Machine Construction and Drawing............. 8vo, 
Weisbach’s Kinematics and the Power of Transmission. (Herrmann— 
Klein.) 2... eee ss eh eee eee oe ee oe ee 8vo, 


Machinery. of Pradamnnon and Governors. (Herrmann—Klein.).8vo, 
Wood’s Elements of Analytical Mechanics. .........-eccccceecceees -OVOy 
Principles of Elementary Mechanics. ........+seeseeeeceeeeses-I2M0, 
Turbines: fi 2 PPPs 26 5 eu. eee ses eoreee «oc dete des Seku ae ete eevee 
The World’s Columbian Exposition of 1863....ccsccsccccses tocccccsece sQt0y 


14 


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METALLURGY. 
Egleston’s Metallurgy of Silver, Gold, and Mercury: 


7 
4 
2 
2 
I 


2 


I 
8 
3 


Pe De E 5 cio 5 oidvencth Pata dee © oe Mile dentate « TN Pee er LS 
ity eer OL EE TIC MCTCUEV.. 5 5.5 «0 ou0i0 visic.o..e> 6. oieiss\sie.sjeree e e.eesges 8vo, 
** Tles’s Lead-smeiting. (Postage 9 cents additional.) ............. 12mo, 
Keep’s Cast Iron...... SOR OOM OER AO Oe Ia ee i aerated 8vo, 
Kunhardt’s Practice of Ore Dressing in Europe..............-...2-0-- 8vo, 
Le Chatelier’s High-temperature Measurements. (Boudouard—Burgess.).12mo, 3 
Metcalf’s Steel. A Manual for Steel-users...............+-2- Bee 12mo, 
Saati GM Ateriais OF MACHINES. . ... os occ cvawoe cece ccien 0 sce Aaa I2mo, 
Thurston’s Materials of Engineering. In Three Parts................ 8vo, 
AMEE AT OTANI SLCC L oie oc cere, os xi0 0 s ances wore didi ec) Be 0) 6.s\ a. eg yus 8vo, 
Part III.—A Treatise on Brasses, Bronzes, and Other Alloys and their 
MEOSTIBTIDUL@ LITE cicie ls c's core cio eo. sie. 07sve auntens mictnae¥a sie sucicioile taik aves 5.5.8 8vo, 
Ulke’s Modern Electrolytic Copper Refining....... See «0 asus e Palen eV Os 
MINERALOGY. 
Barringer’s Description of Minerals of Commercial Value. Oblong, morocco, 
Boyd’s Resources of Southwest Virginia........ POIROT TT REGO. i 8vo, 
Map of Southwest Virginia..........ccecceecscccees Potkersook form, 
Brush’s Manual of Determinative Mineralogy. (Penfield.)............ 8vo, 
Chester’s Catalogue of Minerals...........ccccccccccccvccscees 8vo, paper, 
; Cloth, 
Dictionary of the Names of Minerals...... iW. gid. cee ies 8vo, 
Dana’s System of Mineralogy...........ce.eeee0-: Large 8vo, half leather, 
First Appendix to Dana’s New “System of Mineralogy.”....Large 8vo, 
Text-book of Mineralogy. ihc 2). os'e to's oldies c clad Jaidzle Omar ne 8vo, 
Minerals and How to Study Them.............ccccccccccccces 12mo, 
Catalogue of American Localities of Minerals.............. Large 8vo, 
Manual of Mineralogy and Petrography.............ccceeeeces r2mo, 
Douglas’s Untechnical Addresses on Technical Subjects.............. 12mo, 
Eakle’s Mineral Tables...... pS edirame acs Ria alain lone ki Ries tiv clcidiv esis ce sv eOVO, 
Egleston’s Catalogue of Minerals and Sendnynis RNS AE PEE 8vo, 
Hussak’s The Determination of Rock-torming Minerals. (Smith.) Small 8vo, 
Merrill’s Non-metallic Minerals: Their Occurrence and Uses............. 8vo, 


* Penfield’s Notes on Determinative Mineralogy and Record of ing ng Tests. 
vo, paper, 
Rosenbusch’s Microscopical Physiography of the Rock-making Minerals. 


Ihe Ne GABE CORDS BOR GON COC edie c ORO Geet eer ne 8vo, 

* Tillman’s Text-book of Tiencstant Shirk and packs Geatdietl shes sas ypvereceTs 8vo, 
Williams’s Manual of Lithology............. SiEbighe uo ¥ widieiens SP-es9 +o 0 e eOVO, 

MINING. 

Beard’s Ventilation of Mines............ Ate heer tannin) hepa: 12mo, 
Boyd’s Resources of Southwest Virginia... .......cccccecccccsecccrees 8vo, 
Map of Southwest Virginia............. 02 c cece cece Pocket-book form, 
Douglas’s Untechnical Addresses on Technical Subjects. ............. I2mo, 


* Drinker’s Tunneling, Explosive Compounds, and Rock Drills. 


Dh wNN HK HN HEP NW He BNW DN 


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4to, half morocco, 25 


Eissler’s Modern High Explosives...... raty ahwial stoloserat wld eieneinlsiia = eae 8vo, 
Fowler’s Sewage Works Analyses... ....ccccccccnccscencsccvctieces 12mo, 
Goodyear’s Coal-mines of the Western Coast of the United States...... 12mo, 
Wiganew Manual.of Mining..-............ eens ss. eoads loads io. adm 8vo, 
** Tles’s Lead-smelting. (Postage oc. additional.) .............0008. I2mo, 
Kunhardt’s Practice of Ore Dressing in Europe.............-0000- £2 «80, 
O’Driscoli’s Notes on the Treatment of Gold Ores........ o Ose: MESS 8vo, 
‘* Walke’s Lectures on Explosives...........ccccvsccccccccccccccens 8vo, 
Wilson’s Cyanide ProcesseS.........2.0+2-00- dim ein & sline ote eat eats: r2mo, 

Chlorination ProcesS......cccccceerscceee uae Seas earecsie are wale t2mo, 

13 


—— 


Ret PY HNP YN AP 


50 


Wilson’s Hydraulic and Placer Mining....... WierG Rubs 2 x aco tl ee I2mo, 


Treatise on Practical and Theoretical Mine vamilavios gears supE2m0, 
SANITARY SCIENCE. 
Folwell’s Sewerage. (Designing, Construction, and Maintenance.)...... 8vo, 
Water-supply Engineering. ... 00000 sects ee he ents Siete ee 8vo, 
Fuertes’s Water and Public Héalth: >> oon ht ee eee r2mo, 
Water-filtration Works... cc. ane vise © ik tie oe) ae eee ee I2mo, 
Gerhard’s Guide to Sanitary House-inspection..........:.....------ 16mo, 
Goodrich’s Economical Disposal of Town’s Refuse............... Demy 8vo, 
Hazen’s Filtration of Public Water-supplies........................-- 8vo, 
Leach’s The Inspection and Analysis of Food with Special Reference to State 
Control. oes ee Pee 8vo, 
Mason’s Water-supply. . (Considered Principally from a Sanitary Stand- 
point.) 3d Edition, Rewritten 0 025% Sc. t tee tee ee 8vo, 
Examination of Water. (Chemical and Bacteriological.)........ 12mo, 
Merriman’s Elements of Sanitary Engineering. ......................-. 8vo, 
Ogden’s: Sewer: Design. 2)... ¥ .) ac eed 1 ate eee I2mo, 
Prescott and Winslow’s Elements of Water Bacteriology, with Special Reference 
to Sanitary Water Analysis... 2.2.2.0: . +) suisse eee I2mo, 
* Price’s Handbook on Sanitation)... i.)..3 2.6505 <=2% 45s se neke be eer I2mo, 
Richards’s Cost of Food. A Study in Dietaries.....................- I2mo, 
Cost of Living as Modified by Sanitary Science.................. I2mo, 
Richards and Woodman’s Air, Water, and Food from a Sanitary Stand- 
point... 0d. aoe ew ae Uae ee ele wale oe eileen nr 8vo, 
* Richards and Williams’s The Dietary Computer. ......../........... 8vo, 
Rideal’s Sewage and Bacterial Purification of Sewage.................- 8vo, 
Turneaure and Russell’s Public Water-supplies....................25. 8vo, 
Von Behring’s Suppression of Tuberculosis. (Bolduan.)............. I2mo, 
Whipple’s Microscopy of Drinking-water................+..++..-... 80, 
Woodhull’s Notes and Military Hygiene. ..................-0------- 16mo, 
MISCELLANEOUS. 
Emmons’s Geological Guide-book of the Rocky Mountain Excursion of the 
International Congress of Geologists.................. Large 8vo, 
Ferrel’s Popular Treatise on the Winds.i02..(. <..GGeGeieGhine eo ae 8vo, 
Haines’s American Railway Management. ......................05- I2mo 
Mott’s Composition, Digestibility, and Nutritive Value of Food. Mounted chart. 
Fallacy of the Present Theory of Sound...................-.... 16mo, 
Ricketts’s History of Rensselaer Polytechnic Institute, 1824~-18094. Small 8vo, 
Rostoski’s Serum Diagnosis. “(Bolduan.). .. 2.2. 1.) asso p22. 2 eee I2mo, 
Rotherham’s Emphasized New Testament...................... Large 8vo, 
Steel’s Treatise on the Diseases of the Dog....................-...-.. 8vo, 
Totten’s Important Question in Metrology... 2:5) < ayes succes 8vo, 
The World’s Columbian Exposition of 1803... <<... seer eee Ato, 
Von Behring’s Suppression of Tuberculosis. (Bolduan.)............. I2mo, 


Worcester and Atkinson. Small Hospitals, Establishment and Maintenance, 
and Suggestions for Hospital Architecture, with Plans for a Small 


Hospital... so soci scaieecarneen tn o0.s0 an > Se I2mo, 
HEBREW AND CHALDEE TEXT-BOOKS. 

Green's Grammar of the Hebrew Language......................---- 8vo, 
Elementary Hebrew. Grammar, /.g207 (2. cs SQ ES seen Sen I2mo, 
Hebrew Chrestomathy:= © 0. ..).-a.08'S sis. Ss. See eee 8vo, 
Gesenius’s Hebrew and Chaldee Lexicon to the Old Testament Scriptures. 
Ai regelless).s oe. oe wel bee ee Small 4to, half morocco, 
Letteris’s Hebrew. Bible. occ. occ civine oe 0:00; sos are; een, 0, 0:5, 9 ane lgeet e 8vo, 


16 


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